No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Salinity induced physiological and biochemical changes in plants: An omic approach towards salt stress tolerance
Abstract
Salinity is one of the major threats to sustainable agriculture that globally decrease plant production by impairing various physiological, biochemical, and molecular function. In particular, salinity hampers germination, growth, photosynthesis, transpiration, and stomatal conductance. Salinity decreases leaf water potential and turgor pressure and generates osmotic stress. Salinity enhances reactive oxygen species (ROS) content in the plant cell as a result of ion toxicity and disturbs ion homeostasis. Thus, it imbalances nutrient uptake disintegrates membrane and various ultrastructure. Consequently, salinity leads to osmotic and ionic stress. Plants respond to salinity by modulating various morpho-physiological, anatomical, and biochemical traits by regulating ion homeostasis and compartmentalization, antioxidant machinery, and biosynthesis of osmoprotectants and phytohormones, i. e, auxins, abscisic acid, brassinosteroids, cytokinins, ethylene, gibberellins, salicylic acid, jasmonic acid, and polyamines. Thus, this further modulates plant osmoticum, decreases ion toxicity, and scavenges ROS. Plants upregulate various genes and proteins that participate in salinity tolerance. They also promote the production of various phytohormones and metabolites that mitigate the toxic effect of salinity. Based on recent papers, the deleterious effect of salinity on plant physiology is discussed. Furthermore, it evaluates the physiological and biochemical responses of the plant to salinity along with phytohormone response. This review paper also highlights omics (genomics, transcriptomics, proteomics, and metabolomics) approach to understand salt stress tolerance.
... Furthermore, in the presence of high levels of salinity, excessive accumulation of ions such as sodium (Na + ) and chloride (Cl − ) in plant cells can lead to metabolic toxicity by disrupting cellular respiration, protein synthesis, and other biochemical pathways [9]. This surplus of ions can also hinder the absorption of other essential nutrients for plant growth, like potassium (K + ) and calcium (Ca 2+ ) [10]. Finally, elevated levels of NaCl (sodium chloride) lead to the overproduction of reactive oxygen species (ROS) like hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( • OH), superoxide radical (O2 •− ), and alkoxy radical (RO • ), which can damage cellular components, including proteins, lipids, and nucleic acids [10]. ...
... This surplus of ions can also hinder the absorption of other essential nutrients for plant growth, like potassium (K + ) and calcium (Ca 2+ ) [10]. Finally, elevated levels of NaCl (sodium chloride) lead to the overproduction of reactive oxygen species (ROS) like hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( • OH), superoxide radical (O2 •− ), and alkoxy radical (RO • ), which can damage cellular components, including proteins, lipids, and nucleic acids [10]. It also causes lipid peroxidation and chlorophyll breakdown, ultimately impairing cellular processes and inducing oxidative stress [10]. ...
... Finally, elevated levels of NaCl (sodium chloride) lead to the overproduction of reactive oxygen species (ROS) like hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( • OH), superoxide radical (O2 •− ), and alkoxy radical (RO • ), which can damage cellular components, including proteins, lipids, and nucleic acids [10]. It also causes lipid peroxidation and chlorophyll breakdown, ultimately impairing cellular processes and inducing oxidative stress [10]. ...
Purpose
This study aimed to assess the effect of Sargassum vulgare extracts (SVE) on tomato plants (Solanum lycopersicum L.) exposed to salinity stress.
Methods
We evaluated the impact of SVE concentrations (2%, 5%, and 10%) prepared by the water extraction method using fresh material on the morphophysiological and biochemical parameters of tomato seedlings subjected to salinity (50 mM NaCl).
Results
Our results showed that salinity reduced tomato plant growth compared to the control. However, supplementing stressed plants with lower SVE concentrations, particularly 2%, increased plant height, biomass, and chlorophyll content by 32.24%, 38%, and 55%, respectively, compared to stressed plants without SVE application (positive control). Moreover, 2% of SVE decreased hydrogen peroxide and malondialdehyde levels by 17.24% and 31.54%, respectively. There was also an increase of 23.89%, 133.34%, and 16.36% in the activity of the antioxidant enzymes: glutathione S-transferase (GST), glutathione peroxidase (GPx), and superoxide dismutase (SOD) with treatments of 2%, 5%, and 10% of SVE, respectively, compared to the positive control. Additionally, SVE treatment enhanced indole acetic acid, polyphenols, flavonoids, soluble sugars, and amino acid content. Furthermore, 2% of SVE increased the activities of enzymes involved in carbon and nitrogen metabolism: phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (NAD-MDH), and aspartate aminotransferase (AAT) by 42.47%, 186.23%, and 4.6%, respectively; and glutamine synthase (GS) and glutamate dehydrogenase (GDH) by 185.71% and 0.75%, respectively, in the case of treatment with 10% SVE.
Conclusion
Our research suggests that SVE holds the potential to serve as biostimulant, improving tomato plants’ salt stress tolerance.
Graphical Abstract
... As abiotic stress, salinity in soil inevitably causes negative impacts on the photosynthetic efficiency of plants and contributes to the inhibition of plant growth [9]. In detail, the reduced soil water potential caused by high salinity can disrupt plant-water relationships and reduce cell turgor to lead to osmotic stress [10]. ...
... Therefore, saline-tolerant plants always deal with the detrimental effects of salinity during their growth through certain physiological responses such as upregulating related genes, transcription factors, proteins, and metabolites to maintain the essential processes of photosynthesis and growth [13,14]. For example, the osmoprotectants such as proline (Pro), glycine betaine (GB), sugars, and sugar alcohols that can sustain the cell turgor are synthesized in salinealkali tolerant plants to maintain plant growth and yield [9]. Antioxidative substances including antioxidant enzymatic and non-enzymatic antioxidants are also increased to efficiently quench and scavenge excessive ROS to resist stress and maintain the cell membrane integrity and normal metabolism in the leaf [15,16]. ...
... Arif et al. have described that salinity can affect the ultrastructure, chlorophyll, and carotenoid synthesis in plant cells to interfere with photosynthesis. It was thought to be the salinity in this study that damaged the photosynthetic functions of witchgrass leaves to inhibit photosynthetic function [9], which was manifested directly as the increase in Ci and the decrease in Pn, Tr, and Gs directly. Then, it decreased the leaf length, leaf width and plant height of switchgrass and reduced biological yield eventually. ...
As a potential crop in saline-alkali land, the growth of switchgrass could also be threatened by salt stress. Promoting the growth of switchgrass under salt stress by humic acid has great significance in the utilization of saline-alkali land. In this study, a pot experiment was arranged to investigate the responses of photosynthetic and physicochemical characteristics of switchgrass to HA under salt stress. Results showed that humic acid increased the photosynthetic function of switchgrass and enhanced plant height by 41.1% and dry weight by 26.9% under salt stress. Correlation analysis showed that the membrane aquaporin gene PvPIP1, malondialdehyde, ascorbate peroxidase, abscisic acid, polyamine, and jasmonic acid were important factors affecting the photosynthetic function of switchgrass in this study. Meanwhile, HA reduced the content of malondialdehyde, indicating the alleviation of the membrane damage caused by salt stress. On the other hand, HA upregulated the relative expression of the PvPIP1 gene and activated ascorbate peroxidase, abscisic acid, polyamine, and jasmonic acid in switchgrass to resist salt stress. These improved the membrane stability and promoted the photosynthetic activity of switchgrass to enhance the plant’s tolerance against salt stress and growth. Results from this study are helpful to the efficient growing of switchgrass and the sustainable development of saline-alkali land.
... Water and soil salinization pose constant challenges to crop production worldwide. Salt stress adversely affects plants through various mechanisms, including ion toxicity, osmotic shock, and oxidative stress [1,2]. These combined stresses significantly hinder plant growth, presenting considerable challenges to their ability to thrive. ...
... Plant morphology, physiology, and molecular and biochemical aspects undergo considerable changes under salt stress conditions [3,4]. This disruption occurs directly by reducing plant growth rates and yield or indirectly by causing osmotic, ionic, and nutritional constraints [1]. Reactive oxygen species (ROS) production under salt stress can lead to nucleic acid destruction and lipid peroxidation [2]. ...
Salinity poses a perpetual threat to agricultural lands, presenting an ongoing challenge to global food security. The present study aimed to explore the potential benefits of gibberellic acid (GA3) in enhancing stevia’s tolerance to salt stress. The experimental treatments comprised a control group (C) with 0 mM NaCl, salt stress (S) with 80 mM NaCl, 50 ppm of GA3 (G1), 100 ppm of GA3 (G2), as well as combinations of GA3 with salt stress (G1+S and G2+S). Exposure to saline water (80 mM NaCl) significantly decreased plant growth, water status, and photosynthetic attributes. However, it also led to notable increases in proline, glycine betaine, malondialdehyde (MDA), and antioxidant enzyme activities compared to the control treatment. Application of 100 ppm of GA3 effectively alleviated salt stress by enhancing plant performance under saline conditions, as evidenced by increased aerial (54%) and root (31%) dry weights compared to the control. Additionally, GA3 treatment resulted in elevated activities of polyphenol oxidase (24%), peroxidase (12%), superoxide dismutase (31%), and catalase (11%) while reducing MDA content by 41%, electrolyte leakage by 37%, and hydrogen peroxide by 34%. The use of phytohormones such as GA3 emerges as a promising strategy for mitigating salt stress-induced damage. It not only enhances plant performance but also reduces oxidative stress, offering protection against the detrimental effects of soil salinization.
... Increment in biomass accumulation was also observed with the application of 7.0 mM of proline in plants irrigated with water of 3.0 dS m -1 (9.80 g per plant), with an increase of 5.26% compared to plants without proline application (0 mM) and kept under the same irrigation condition. Such reductions show the effects on photosynthetic pigments, fluorescence, and gas exchange, which limit the support necessary to regulate the plant's metabolism, making it necessary to release energy to maintain root homeostasis, hence neglecting shoot growth (ARIF et al., 2020). This situation has already been alleviated in the root system by the application of proline, freeing up energy for shoot growth (BAUDUIN et al., 2022). ...
... Proline application, in turn, caused a decrease in RDM at all salinity levels, and the lowest value was obtained when the highest concentration of proline (15 mM) was associated with the highest water salinity (3.0 dS m -1 ), leading to a value of 2.72 g per plant, which is 12.82% lower than the maximum estimated value (4.56%) found in plants without proline application and under the same irrigation condition (2.85 g per plant). Increase in root biomass due to increased salt stress is associated with the strategy of increasing the root area as a way to attenuate the osmotic effect of salinity (ZHAO et al., 2020), and at high salinity levels, the osmotic potential decreases to values that limit root expansion, so it becomes necessary to increase osmolyte production to values that do not impair root growth (ARIF et al., 2020). This situation explains the reduction in RDM accumulation caused by the application of proline, which already maintains osmotic regulation with the soil at values that do not require the release of more energy for root growth (SHAFI; ZAHOOR; MUSHTAQ, 2019). ...
Water sources in the Brazilian semi-arid region commonly contain high levels of dissolved salts in their composition, standing out as one of the abiotic stresses that limit the expansion of irrigated fruit growing, especially salt stress-sensitive crops such as sour passion fruit. Thus, the use of elicitors, such as proline, can be an effective alternative to mitigate salt stress in plants. In this context, the objective of this study was to evaluate the effects of foliar application of proline on chlorophyll fluorescence, growth, quality and tolerance of sour passion fruit irrigated with saline water during the seedling formation phase. The experiment was conducted from July to October 2022, under greenhouse conditions in Campina Grande, PB, Brazil, using a completely randomized design, in a 5 × 4 factorial scheme, with five levels of electrical conductivity of irrigation water - ECw (0.6, 1.2, 1.8, 2.4 and 3.0 dS m⁻¹) and four concentrations of proline (0, 5, 10 and 15 mM), with four replicates and two plants per plot. Water salinity from 0.6 dS m⁻¹ reduces the maximum fluorescence, variable fluorescence, quantum yield of photosystem II and growth of ‘BRS GA1’ sour passion fruit seedlings. Foliar application of proline at concentrations ranging from 6 to 8.05 mM increases the growth in plant height, stem diameter and leaf area of sour passion fruit seedlings. The sour passion fruit genotype ‘BRS GA1’ is sensitive to water salinity, with a salinity threshold level of 0.6 dS m⁻¹ and a reduction per unit increase in electrical conductivity of 10.49%.
Keywords
Passiflora edulis Sims; Salinity; Osmolyte synthesis.
... Due to the salinity effect's genetic processes and food deficits, panicle sterility is caused in many rice cultivars, particularly during the pollination and fertilization stages (Hassanuzzaman et al. 2009;Pariha et al. 2015). Multiple studies have indicated that salt stress after fertilization causes panicle sterility, decreasing grain setting, pollen-bearing capability, stigmatic surface, or both (Abdullah et al. 2001;Arif et al. 2020). Lower grain yield during salt stress is due to a lack of glucose transition to vegetative and spikelet development (Liu et al. 2022a, b). ...
... Furthermore, salinity stress significantly reduces soluble sugar translocation to superior and inferior spikelets and suppresses starch synthase activity during grain development, contributing to poorer rice grain yield (Abdullah et al. 2001;Arif et al. 2020); Chen et al. 2019). Salinity stress negatively impacts various aspects of rice growth, including reduced spikelet number, panicle length, number of tillers per plant, florets number, and 1000-grain weight (Aref et al. 2012). ...
Low yields of crops, especially rice, are caused by climate change and environmental stress concerns such as drought, temperature fluctuations, and salinity in arid and semi-arid locations around the globe. Rice is one of the essential crops for human consumption and one of the most commonly farmed cereals on the planet earth, but its growth is severely retarded by excessive salt, which influences rice development and production, leading to economic loss. Salt stress induces osmotic stress and ionic toxicity in rice by altering the environment, leading to water deprivation and accumulation of toxic ions, thereby triggering specific physiological and molecular responses in the rice plants. Many factors may affect rice production and cereal quality via its interaction with salinity. This review focuses on some influential factors (photosynthesis, osmosis, micro and macronutrients, microbial flora, rice growth, development, and genes) that may reduce rice production in saline soils. The review also describes the responsive mechanism of rice to salinity and the genetic susceptibility of rice. In light of the challenges posed by the growing global population and limited agricultural land, it is imperative to consider the influential factors discussed in this review, along with genetic susceptibility to improve rice production in terms of quantity and quality under saline soil conditions.
... Salinity stress causes osmotic stress and ion toxicity by increasing https://plantsciencetoday.online the assimilation of Na + ions and decreasing the Na + /K + ratio due to lower osmotic potential within the plant roots. Further, these ionic imbalance affects the uptake and transport of other important essential mineral nutrients in target cells and hamper the crucial plant processes and functions (3). Salinity in soil can impact plant properties such as nutrient absorption, growth, and yield (4). ...
Salt stress is one of the major factors that decreases wheat yield. The aim of this study is to examine the effects of K, SA, and GABA application on yield components, grain yield, and nutrient uptake in high-salinity in wheat genotypes. The research was conducted as a split plot based on a randomized complete block design with three replications under normal as control, and salinity (8 dS/m) conditions. The main plots included foliar application with growth stimulants (K, SA, GABA, and control), and subplots encompassed seven wheat genotypes. The salinity caused a 49.95% decrease in grain yield compared to normal conditions. The Mihan genotype showed the highest grain yield when treated with potassium (10970.6 kg/ha), GABA (11370.1 kg/ha), and salicylic acid (10650.1 kg/ha) under non-stress conditions. Furthermore, under salinity conditions, the Mihan genotype sprayed with potassium (7036.1 kg/ha) and GABA (5070.1 kg/ha) produced the maximum grain yield. Foliar spraying with potassium and GABA in both conditions improved the Fe, Cu, Zn, and Mn content in grains compared to control. Exposure to salt stress caused a decrease in iron (50.05%), copper (27.86%), and magnesium (18.86%) content in the seeds. Treatments with potassium and GABA in both conditions increased the Fe, Cu, Zn, and Mn content in grain. The highest nitrogen and potassium content and lowest sodium content in leaves were observed in Mihan genotype sprayed with K. Therefore, foliar application of K and GABA can moderate the effects of salinity on wheat.
... Excessive sodium ions in salt soil or excessively salinized irrigation water can decrease water absorption efficiency, increase water leakage, and reduce root cell osmotic potential [16]. According to Arif et al. [17], sodium ions can disturb vital cellular functions in plants by creating an imbalance in the absorption of potassium and other crucial ions by target cells. Under high salt conditions, Na ions induce ionic toxicity and osmotic stress [15,16]. ...
Plants spontaneously accumulate γ-aminobutyric acid (GABA), a nonprotein amino acid, in response to various stressors. Nevertheless, there is limited knowledge regarding the precise molecular mechanisms that plants employ to cope with salt stress. The objective of this study was to investigate the impact of GABA on the salt tolerance of eight distinct varieties of bread wheat (Triticum aestivum L.) by examining plant growth rates and physiological and molecular response characteristics. The application of salt stress had a detrimental impact on plant growth markers. Nevertheless, the impact was mitigated by the administration of GABA in comparison to the control treatment. When the cultivars Gemmiza 7, Gemmiza 9, and Gemmiza 12 were exposed to GABA at two distinct salt concentrations, there was a substantial increase in both the leaf chlorophyll content and photosynthetic rate. Both the control wheat cultivars and the plants exposed to salt treatment and GABA treatment showed alterations in stress-related biomarkers and antioxidants. This finding demonstrated that GABA plays a pivotal role in mitigating the impact of salt treatments on wheat cultivars. Among the eight examined kinds of wheat, CV. Gemmiza 7 and CV. Gemmiza 11 exhibited the most significant alterations in the expression of their TaSOS1 genes. CV. Misr 2, CV. Sakha 94, and CV. Sakha 95 exhibited the highest degree of variability in the expression of the NHX1, DHN3, and GR genes, respectively. The application of GABA to wheat plants enhances their ability to cope with salt stress by reducing the presence of reactive oxygen species (ROS) and other stress indicators, regulating stomatal aperture, enhancing photosynthesis, activating antioxidant enzymes, and upregulating genes involved in salt stress tolerance.
... In saline soils, NaCl accounts for 50-80% of the total soluble salts, resulting in osmotic stress, hindering water uptake by roots, and concentrations of toxic Na + and/or Cl − in plant tissues (Zeeshan et al. 2020). Salt toxicity also affects plant photosynthetic efficiency (Arif et al. 2020). Photosynthetic activity in plants is strongly associated with agricultural productivity and yield. ...
... In this investigation, salinity stress showed a greater reduction in chlorophyll a ( Figure 2B) and chlorophyll b ( Figure 2C) for the maize hybrid (FH-1046) compared to hybrid V 1 (YH-5427); however, the foliar application of CuO-NPs improved all of these physiological attributes (Figure 2). There is a link between salinity-induced oxidative stress that causes antagonistic effects on plant growth, physio-biochemical, anatomical, metabolic and enzymatic activities [42]. Saline conditions alter photosynthesis due to structural variations in the chloroplast in maize crop varieties [43]. ...
Citation: Shafiq, H.; Shani, M.Y.; Ashraf, M.Y.; De Mastro, F.; Cocozza, C.; Abbas, S.; Ali, N.; Zaib-un-Nisa; Tahir, A.; Iqbal, M.; et al. Copper Oxide Nanoparticles Induced Growth and Physio-Biochemical Changes in Maize (Zea mays L.) in Saline Soil. Plants 2024, 13, 1080. https:// Abstract: Research on nanoparticles (NPs) is gaining great attention in modulating abiotic stress tolerance and improving crop productivity. Therefore, this investigation was carried out to evaluate the effects of copper oxide nanoparticles (CuO-NPs) on growth and biochemical characteristics in two maize hybrids (YH-5427 and FH-1046) grown under normal conditions or subjected to saline stress. A pot-culture experiment was carried out in the Botanical Research Area of "the University of Lahore", Lahore, Pakistan, in a completely randomized design. At two phenological stages, both maize hybrids were irrigated with the same amount of distilled water or NaCl solution (EC = 5 dS m −1) and subjected or not to foliar treatment with a suspension of CuO-NPs. The salt stress significantly reduced the photosynthetic parameters (photosynthetic rate, transpiration, stomatal conductance), while the sodium content in the shoot and root increased. The foliar spray with CuO-NPs improved the growth and photosynthetic attributes, along with the N, P, K, Ca, and Mg content in the roots and shoots. However, the maize hybrid YH-5427 responded better than the other hybrid to the saline stress when sprayed with CuO-NPs. Overall, the findings of the current investigation demonstrated that CuO-NPs can help to reduce the adverse effects of salinity stress on maize plants by improving growth and physio-biochemical attributes.
... Ion stress induced by toxic ions such as sodium (Na + ) and chloride (Cl -) (Sofy et al., 2020), particularly the excessive accumulation of Na + ions (Niu et al., 2017), contributes to the indirect effects. Oxidative stress arises from the excessive generation of harmful ROS (Arif et al., 2020). To withstand these stress factors, plants employ tolerance mechanisms and develop various physiological and biochemical adaptations. ...
In this study, the aim was to determine some morphological, physiological, and biochemical changes in non-grafted plants of OHxF 97, OHxF 333, Fox 11, and BA 29 rootstocks under NaCl stress. NaCl (0 mM, 20 mM, 40 mM, and 80 mM) was applied to the rootstocks planted in 18-liter pots with irrigation water repeated over two years. Under NaCl stress, plant height, plant diameter, and leaf area decreased in all rootstocks. Additionally, Fox 11 and BA 29 rootstocks were more adversely affected by NaCl stress to leaf necrosis. The amounts of chl a, chl b, and total chl decreased in Fox 11 rootstock with moderate and severe stress treatments. Carotenoid content in the leaves, especially under severe stress conditions, showed a decrease in Pyrus rootstocks. Under NaCl stress, the leaves of Fox 11 were rich in proline. MDA content generally increased with NaCl stress compared to the control in Fox 11 and BA 29. Although significant changes in plant nutrients were generally not observed with NaCl, a significant decrease in the amount of K+ in the leaves of Fox 11 was identified. Consequently, Fox 11 and BA 29 rootstocks exhibit sensitivity to NaCl stress, whereas OHxF rootstocks demonstrate greater tolerance.
... The expanding salt stress has a severe effect on Pakistan's economy (ur Rehman et al., 2021). Many cereal crops have a negative correlation with salt stress in terms of food production (Arif et al., 2020;ur Rehman et al., 2021). ...
Salt stress is a serious threatening factor for cereal crops such as maize (Zea mays L.) by affecting their growth and development. In the current era, the requirement for staple crops is increasing, so it is important to screen out salt-tolerant genotypes. For this purpose, a pot experiment was designed within three replications on ten different genotypes of the maize. The plants were planted in plastic pots and salt stress (0, 40, 70, 100 mM) was maintained. The salt stress induced a noticeable reduction in plant growth traits (shoot length, root length, shoot, root fresh and dry weight, and leaf area (LA). The photosynthetic pigments as Chl a, Chl b, Total chlorophyll, and carotenoids. The elevated stress levels cause an intensive accumulation rate of MDA (malondialdehyde) and H2O2 (hydrogen peroxide) resulting from stress exposure and ultimately damaged the membrane-bounded organelles. The Flavonoid and phenolic contents increased as the salt stress level increased, this increase was higher in Pearl and least in Sadaf. The activity of cellular antioxidants (SOD) is significantly enhanced under stress to quench oxidative stress. Our results revealed the genotype Sadaf as sensitive and salt tolerant genotypes were as Pearl > Sahiwal 2002 > Pioneer > MMRI(Y). Based on screening, the tolerant genotypes have the potential to grow under saline conditions. However, further research is needed to explore the genetic basis of salt tolerance in these genotypes.
... Plant responses to salinity are multifaceted, involving complex genetic, biochemical, and physiological adaptations. In tomatoes, these include selective ion transport and sequestration, osmotic adjustment through organic osmolytes, and an augmented antioxidant defense system [12][13][14]. However, the variability among tomato cultivars in these adaptive responses is substantial and necessitates a comparative analysis to identify and utilize salt-tolerant varieties effectively [15]. ...
Background: Soil salinity is an escalating problem that significantly reduces crop yield,
... Kalaji et al. (2011) have suggested that the sensitive barley genotypes' susceptibility to salt stress may be, among other things, a result of the low capacity of some pathways such as the Mehler reaction (water-water cycle), which has a protective function in the case of a limited supply of PSII in water. This also helps maintain ATP formation and allows efficient water circulation in the cell in plants with osmotic stress (Osmond and Grace, 1995;Arif et al., 2020). ...
Introduction
In the Near East and North Africa (NENA) region, crop production is being affected by various abiotic factors, including freshwater scarcity, climate, and soil salinity. As a result, farmers in this region are in search of salt-tolerant crops that can thrive in these harsh environments, using poor-quality groundwater. The main staple food crop for most of the countries in this region, Tunisia included, is barley.
Methods
The present study was designed to investigate the sensitivity and tolerance of six distinct barley genotypes to aridity and salinity stresses in five different natural field environments by measuring their photosynthetic activity.
Results and discussion
The results revealed that tolerant genotypes were significantly less affected by these stress factors than sensitive genotypes. The genotypes that were more susceptible to salinity and aridity stress exhibited a significant decline in their photosynthetic activity. Additionally, the fluorescence yields in growth phases J, I, and P declined significantly in the order of humid environment (BEJ), semi-arid site (KAI), and arid environment (MED) and became more significant when salt stress was added through the use of saline water for irrigation. The stress adversely affected the quantum yield of primary photochemistry (φP0), the quantum yield of electron transport (φE0), and the efficiency by trapped excitation (ψ0) in the vulnerable barley genotypes. Moreover, the performance index (PI) of the photosystem II (PSII) was found to be the most distinguishing parameter among the genotypes tested. The PI of sensitive genotypes was adversely affected by aridity and salinity. The PI of ICARDA20 and Konouz decreased by approximately 18% and 33%, respectively, when irrigated with non-saline water. The reduction was even greater, reaching 39%, for both genotypes when irrigated with saline water. However, tolerant genotypes Souihli and Batini 100/1B were less impacted by these stress factors.
The fluorescence study provided insights into the photosynthetic apparatus of barley genotypes under stress. It enabled reliable salinity tolerance screening. Furthermore, the study confirmed that the chlorophyll a fluorescence induction curve had an inflection point (step K) even before the onset of visible signs of stress, indicating physiological disturbances, making chlorophyll fluorescence an effective tool for identifying salinity tolerance in barley.
... The Citrus fruit sector is the largest fruit category on an international scale. It is ranked among the most important branches of the national economy; Despite the importance of citrus growing, as all agricultural crop is facing increasing biotic and abiotic stresses, in the main production areas, whose salinity is one of the major abiotic stresses that negatively affects productivity and crop quality [1]. They are among the plant species most sensitive to salts, It is accepted that the tolerance of citrus fruits to salinity varies greatly between species and depends mainly on the rootstock [2,3,4]. ...
Salinity is an abiotic constraint, the consequences of which affect both the production and the quality of citrus fruits. The use of rootstocks resistant and / or tolerant to this stress is necessary to overcome this problem. This work aims to compare in vitro, the behavior of callus of citrus rootstocks with respect to successive concentrations of NaCl, on morphological and physiological parameters, such as: fresh weight; Dry weight; Callus growth, proline content; Total sugars content, and Chloride content. Calli tested in vitro of eight rootstock genotypes including: Poncirus trifoliata (PT), citrange Carrizo (CC), Citrumelo 4475 (C); Citrus volkameriana (CV), citrange Troyer (CT), Citrandarin (CD), Lime rangpur (LR), Mandarin cleopatre (MC), induced in MT medium (Murashige and Tucker), with the presence of 2,4-D (2,4-dichlorophenoxyacetic acid) , and BAP (Benzylaminopurine), then transferred to MT medium (Murashige and Tucker), added successive concentrations of sodium chloride: NaCl (1 g / l; 3 g / l; 6g / l), for a period of 2 months. The results obtained show that the application of stress leads to a decrease in fresh weight, and dry weight, as well as the growth of calluses compared to control callus. On the other hand, there is an increase in the content of proline, and total soluble sugars, as well as the significant accumulation of chloride ions in stressed calluses, compared to control calluses. The accumulation of proline and total soluble sugars could be an indicator of tolerance to salinity in the callus of the rootstocks studied.
... Experiments have highlighted the positive impact of the plant growthpromoting inter-root bacterium Brachybacterium saurashtrense on nitrogen-deficient peanuts under salt stress (Alexander et al., 2022). Transcription factors (TFs) play a crucial role in modulating and regulating the expression of different genes under salinity conditions, demonstrating gene expression association with the promoter region (Arif et al., 2020). Currently, numerous TFs have been identified to play pivotal roles in the growth and development of peanuts, with the WRKY family being noteworthy. ...
Introduction
Soil salinization poses a significant environmental challenge affecting plant growth and agricultural sustainability. This study explores the potential of salt-tolerant endophytes to mitigate the adverse effects of soil salinization, emphasizing their impact on the development and resistance of Arachis hypogaea L. (peanuts).
Methods
The diversity of culturable plant endophytic bacteria associated with Miscanthus lutarioriparius was investigated. The study focused on the effects of Bacillus tequilensis, Staphylococcus epidermidis, and Bacillus siamensis on the development and germination of A. hypogaea seeds in pots subjected to high NaCl concentrations (200 mM L⁻¹).
Results
Under elevated NaCl concentrations, the inoculation of endophytes significantly (p < 0.05) enhanced seedling germination and increased the activities of enzymes such as Superoxide dismutase, catalase, and polyphenol oxidase, while reducing malondialdehyde and peroxidase levels. Additionally, endophyte inoculation resulted in increased root surface area, plant height, biomass contents, and leaf surface area of peanuts under NaCl stress. Transcriptome data revealed an augmented defense and resistance response induced by the applied endophyte (B. tequilensis, S. epidermidis, and B. siamensis) strain, including upregulation of abiotic stress related mechanisms such as fat metabolism, hormones, and glycosyl inositol phosphorylceramide (Na⁺ receptor). Na⁺ receptor under salt stress gate Ca²⁺ influx channels in plants. Notably, the synthesis of secondary metabolites, especially genes related to terpene and phenylpropanoid pathways, was highly regulated.
Conclusion
The inoculated endophytes played a possible role in enhancing salt tolerance in peanuts. Future investigations should explore protein–protein interactions between plants and endophytes to unravel the mechanisms underlying endophyte-mediated salt resistance in plants.
... Furthermore, severe salt stress can cause excessive stomatal closure as a response to water shortage (Taiz et al., 2017). Phytohormone application may have alleviated this excessive closure, allowing stomata to remain more open and thus increasing the transpiration rate (Arif et al., 2020). The down-regulation of photosynthesis under salt stress is primarily attributed to a limitation in RuBisCO activity, which has been identified as one of the major constraints (Singh et al., 2022). ...
Phytohormones play a pivotal role in regulating plant growth and responding to salt stress, aiding in signal perception and defense system mediation. With this, the objective of the present study was to assess the impact of phytohormone application in mitigating the harmful effects of salt stress on radish. Three levels of NaCl (0, 50, and 100 mM) and five phytohormones (jasmonic acid, salicylic acid, cytokinin, gibberellin, and polyamine) plus a control treatment (deionized water) were studied. The application of phytohormones such as jasmonic acid and cytokinin improved photosynthetic efficiency, and diameter, length, and total soluble solids content of tuber. Under salt stress conditions, plants showed adaptations in gas exchange, varying their rates of photosynthesis and transpiration. Furthermore, an effective balance between carbon assimilation and water loss was observed in some plants. The application of phytohormones counteracted salt stress, safeguarding chlorophyll, sustaining gas exchange, and promoting plant growth of radish. Consequently, use of phytohormones represents an alternative for radish cultivation under salt stress.
Key words:
Raphanus sativus; chlorophyll indices; gas exchange; growth
... The salinity caused a reduction in the root and shoot lengths, resulting in decreased plant growth. This growth inhibition may be due to salt stress that causes ionic toxicity and a disturbance in metabolic activity, leading to a manifested disruption in photosynthetic activity; thus a decrease in growth biomass was obvious [33]. The current investigation also depicted that salinity caused a reduction in chlorophyll contents ( Figure 3A-C) and nutrient imbalance ( Figure 4); subsequently, a reduction in growth and biomass ( Figure 1) was noticed. ...
... The salinity caused a reduction in the root and shoot lengths, resulting in decreased plant growth. This growth inhibition may be due to salt stress that causes ionic toxicity and a disturbance in metabolic activity, leading to a manifested disruption in photosynthetic activity; thus a decrease in growth biomass was obvious [33]. The current investigation also depicted that salinity caused a reduction in chlorophyll contents ( Figure 3A-C) and nutrient imbalance ( Figure 4); subsequently, a reduction in growth and biomass ( Figure 1) was noticed. ...
The present investigation was conducted to explore the role of potassium nutrition in improving biomass and physio-chemical alterations to reduce the adverse effects of salinity in mungbean. A sand-culture experiment was carried out under different salinity levels (0, 50, and 100 mM NaCl) with two levels of potassium (0 and 50 mM K2SO4) and two mungbean cultivars (NM-92 and Ramzan), and the alterations in mungbean biomass and metabolic activities were investigated. The results suggested that salinity significantly reduced the biomass, nitrate reductase activity (NRA), nitrite reductase activity (NiRA), total soluble proteins, chlorophyll a, chlorophyll b, total chlorophyll, nitrogen, potassium, calcium, magnesium, and phosphorous contents in both mungbean cultivars in comparison to the control. However, K2SO4 at 50 mM significantly improved all the parameters in both mungbean cultivars except for the sodium content. A significant increase in the total free amino acids, carotenoids, and sodium content in both mungbean cultivars was observed due to salt stress. Moreover, principal component analysis and heatmaps were developed individually for both mungbean cultivars to assess the variability and correlation among the studied attributes under all applied treatments. Under saline conditions, the mungbean ‘Ramzan’ showed more marked reductions in almost all the growth parameters as compared to ‘NM-92’. The results suggest that the application of K2SO4 ameliorates the adverse effects of salinity by regulating osmolyte production, NRA, and NiRA, thus promoting plant growth and productivity.
... Antioxidant enzymes consist of CAT, SOD and peroxidase (POD), which react with various types of ROS and convert them into H 2 O and other substances. Non-enzymatic antioxidants including ascorbic acid (AsA), glutathione (GSH) is mainly involved in ROS scavenging as cofactors for various enzymes (Arif et al. 2020;Hasanuzzaman et al. 2021). Furthermore, to maintain osmotic balance, the plant accumulates various osmoregulatory substances, which reduce intracellular osmotic pressure and safeguard water requirements (Wang et al. 2023). ...
Salt stress has become one of the most widespread abiotic stresses globally, negatively affecting crop growth, development, and yield. Rice is an important economic crop affected by salt stress. This study used Huanghuazhan (‘HHZ’) as the test material to investigate the mitigating effect of spraying Hemin (alone) or with Hb and ZnPP (in combination) on the oxidative damage induced by 100 mM NaCl solution. The results showed that Hemin treatment maintained the growth of rice seedlings under NaCl stress and improved shoot (plant height, stem base width, leaf area) and root (root length, root surface area, root volume, average root diameter and number of root tips) morphological parameters. In addition, exogenous Hemin increased root activity, raised the content of various photosynthetic pigments, improved leaf structure, and increased the area of vascular bundles, which sustained photosynthesis and promoted the accumulation of biomass. Furthermore, Hemin reduced the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2), by activating the activities of various antioxidant enzymes and increasing the content of non-enzymatic antioxidants. While ZnPP (a specific inhibitor of heme oxygenase-1 (HO-1)) and Hb (CO scavenger) reversed the positive regulation of Hemin, and the indexes (biomass of rice seedlings, root activity, and the activity of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)) somewhat decreased. In conclusion, this study demonstrated that Hemin reduced ROS accumulation, maintained leaf structure and photosynthetic pigment content, and mitigated the adverse effects of oxidative damage caused by NaCl stress in rice through improving the antioxidant capacity of leaves and roots. This research provides a theoretical basis for Hemin to regulate salt tolerance in other crops. However, the molecular mechanisms involved in Hemin regulation need to be further explored.
... Different strategies have been adopted to improve the stress sensing and adaptation ability, but nanotechnology has gained a much greater attention of the scientist to cope with variety of stresses both biotic and abiotic. Nanomaterial are not only involved in adaptation and stress tolerance but also reported to improve the plant growth and crop yield (Arif et al., 2020) (Fig. 7). ...
... Salinity stress involves ionic and osmotic stresses: osmotic stress is the first stress experienced when a plant is exposed to saline soil while ionic stress occurs later when salt levels reach a threshold beyond which the plant cannot maintain ion homeostasis and growth [6]. Both osmotic and ionic action of salinity ultimately cause oxidative stress affecting various physiological and biochemical processes in plants [7,8], which eventually drastically impacts overall plant growth, development, metabolism, and productivity [9]. In addition, the changing climatic conditions and their effects on farming worsen the salinity problem and further threaten the stability of agricultural production. ...
Background
Salinity is one major abiotic stress affecting photosynthesis, plant growth, and development, resulting in low-input crops. Although photosynthesis underlies the substantial productivity and biomass storage of crop yield, the response of the sunflower photosynthetic machinery to salinity imposition and how H2S mitigates the salinity-induced photosynthetic injury remains largely unclear. Seed priming with 0.5 mM NaHS, as a donor of H2S, was adopted to analyze this issue under NaCl stress. Primed and nonprime seeds were established in nonsaline soil irrigated with tape water for 14 d, and then the seedlings were exposed to 150 mM NaCl for 7 d under controlled growth conditions.
Results
Salinity stress significantly harmed plant growth, photosynthetic parameters, the structural integrity of chloroplasts, and mesophyll cells. H2S priming improved the growth parameters, relative water content, stomatal density and aperture, photosynthetic pigments, photochemical efficiency of PSII, photosynthetic performance, soluble sugar as well as soluble protein contents while reducing proline and ABA under salinity. H2S also boosted the transcriptional level of ribulose 1,5-bisphosphate carboxylase small subunit gene (HaRBCS). Further, the transmission electron microscope showed that under H2S priming and salinity stress, mesophyll cells maintained their cell membrane integrity and integrated chloroplasts with well-developed thylakoid membranes.
Conclusion
The results underscore the importance of H2S priming in maintaining photochemical efficiency, Rubisco activity, and preserving the chloroplast structure which participates in salinity stress adaptation, and possibly sunflower productivity under salinity imposition. This underpins retaining and minimizing the injury to the photosynthetic machinery to be a crucial trait in response of sunflower to salinity stress.
... This stress induces Reactive Oxygen Species (ROS), damaging membranes, integrity, signalling and compartmentalization process (Hasanuzzaman et al., 2020). Salt's impact and its secondary stressors impede progress in breeding salt-tolerant crops (Arif et al., 2020). Salinization from natural/human factors limits crop output. ...
Background: Salinity impacts physiological processes, including germination, seedling development, ionic balanc e and water relations, leading to growth inhibition. Mung bean's early stage is susceptible to salt stress. Our study aimed to mitigate salt stress at early stage using zinc oxide nanoparticles (ZnO-NPs) to enhance mung bean tolerance. Methods: Pot experiment was carried out to incorporate ZnO-NPs into mung bean seedlings. Two Mung bean genotypes, TMB-37 (tolerant) and MH-1314 (sensitive), were chosen. Seeds were primed with ZnO-NPs at various concentrations (0.00 ppm, 50 ppm, 100 ppm, 500 ppm and 1000 ppm) and shown in saline soil. Result: ZnO-NP priming notably increased germination percentage, shoot length and shoot dry weight in both genotypes. In 25-days-old seedlings, ZnO-NPs elevated antioxidant enzyme activity, proline content, especially superoxide dismutase (SOD) and peroxidase (POX) activity, while reducing lipid peroxidation and membrane injury. 1000 ppm ZnO-NPs had the negative impact on the root trait of sensitive genotype. Lower doses of ZnO-NP (50 ppm) concentrations was very effective in mitigating the adverse effect of salinity stress in both the genotypes offering a key approach for Mung bean's salt stress mitigation.
... It induces osmotic stress and restricts water absorption from the soil, leading to ionic stress due to high stages of actually toxic salt ions inside plant cells (Savvas et al., 2005). High salinity reduces photosynthetic indices, total chlorophyll content, and degrades chloroplast structure by minimizing grana (Arif et al., 2020). Many symptoms, including an increase in leaf succulence and thickness, abscission of leaves, necrosis of root and shoot and a decrease in leaf area and internode length, are frequently present in reaction to these changes. ...
Syzygium cumini L., known commonly as jamun, is a fruit tree with significant adaptability to diverse environmental conditions, particularly saline soils. This review comprehensively explores the adaptation mechanisms of jamun to saline environments and its agricultural significance on a global scale. Given the increasing soil salinization worldwide, understanding the resilience of crops like jamun is crucial for sustainable agricultural practices in salt-affected regions. Jamun is native to the Indian subcontinent but has been cultivated in tropical and subtropical regions worldwide. Its ability to withstand various abiotic stresses, especially soil salinity, makes it an ideal candidate for cultivation in areas prone to such conditions. This review highlights the physiological and biochemical responses of jamun to high salinity, including ion regulation, osmotic adjustment, and antioxidant activity. These mechanisms help the plant maintain growth and productivity in environments where many other crops fail. Additionally, the review discusses the importance of jamun in traditional medicine and its nutritional benefits, emphasizing its potential for enhancing food security in saline-affected areas. The fruit's rich composition of vitamins, antioxidants, and minerals underscores its nutritional value, making it a beneficial addition to the diet in regions with limited crop diversity due to salinity. Furthermore, the paper addresses the agricultural practices conducive to maximizing jamun's yield in saline environments, including suitable propagation techniques and water management strategies. It also explores the genetic diversity within Syzygium cumini species, which could be leveraged to breed varieties with enhanced salt tolerance and better fruit quality. In conclusion, the global cultivation of jamun not only contributes to biodiversity but also offers a viable solution for agricultural productivity in salt-impacted soils. Continued research and development efforts are essential to optimize cultivation practices and expand the use of jamun in saline agriculture.
... Accordingly, drought and salt stresses give rise to several molecular, physiological, biochemical, and morphological changes in crop, such as up-regulated or down-regulated expression of relative genes, the accumulation of reactive oxygen species (ROS) and membrane osmotic regulators, ion toxicity, stomatal closure, the inhibition of photosynthesis, etc. [4][5][6][7][8][9][10]. Roots architecture, for its duty of absorbing and transporting water and nutrients, is pivotal to perceiving drought and salinity stresses. ...
Drought and salinity stress reduce root hydraulic conductivity of plant seedlings, and melatonin application positively mitigates stress-induced damage. However, the underlying effect of melatonin priming on root hydraulic conductivity of seedlings under drought–salinity combined remains greatly unclear. In the current report, we investigated the influence of seeds of three wheat lines’ 12 h priming with 100 μM of melatonin on root hydraulic conductivity (Lpr) and relevant physiological indicators of seedlings under PEG, NaCl, and PEG + NaCl combined stress. A previous study found that the combined PEG and NaCl stress remarkably reduced the Lpr of three wheat varieties, and its value could not be detected. Melatonin priming mitigated the adverse effects of combined PEG + NaCl stress on Lpr of H4399, Y1212, and X19 to 0.0071 mL·h−1·MPa−1, 0.2477 mL·h−1·MPa−1, and 0.4444 mL·h−1·MPa−1, respectively, by modulating translation levels of aquaporin genes and contributed root elongation and seedlings growth. The root length of H4399, Y1212, and X19 was increased by 129.07%, 141.64%, and 497.58%, respectively, after seeds pre-treatment with melatonin under PEG + NaCl combined stress. Melatonin -priming appreciably regulated antioxidant enzyme activities, reduced accumulation of osmotic regulators, decreased levels of malondialdehyde (MDA), and increased K+ content in stems and root of H4399, Y1212, and X19 under PEG + NaCl stress. The path investigation displayed that seeds primed with melatonin altered the modification of the path relationship between Lpr and leaf area under stress. The present study suggested that melatonin priming was a strategy as regards the enhancement of root hydraulic conductivity under PEG, NaCl, and PEG + NaCl stress, which efficiently enhanced wheat resistant to drought–salinity stress.
... In agreement, stable DW was observed in the control and 3000 mgL −1 treatments; however, it increased in the 6000 mgL −1 treatments. Some salt-tolerant plants show adaptations by improving water use efficiency, allowing them to extract water from saline soils while minimizing water loss through transpiration [45][46][47][48]. ...
Salinity is a significant factor restricting plant growth and production. The effect of salinity stress on different growth parameters of 111 fenugreek genotypes was examined in an experiment with three salinity levels (0, 3000, 6000 mgL−1). A completely randomized block design with two replicated pots per treatment was used. Non-significant treatment effects were observed on fresh weight (FW); however, all traits showed significant genotype-by-treatment (GxT) interactions. This GxT was reflected in substantial SNP x environment interactions. Of 492 significant SNPs associated with the measured traits, 212 SNPs were linked to the correlated traits using an arbitrary threshold of three. Several SNPs were associated with FW and dry weight, measured under the same salinity treatment. The correlation between both traits was 0.98 under the three salinity treatments. In addition, 280 SNPs with conditional neutrality effects were mapped. The identified SNPs can be used in future marker-assisted breeding programs to select salt-tolerant genotypes. The results of this research shed light on the salt-tolerant properties of fenugreek.
... For example, drought stress can reduce water availability to plant roots, which can limit the uptake of nutrients from the soil (Seleiman et al., 2021;Zuidersma et al., 2020). High salinity can also reduce nutrient uptake by creating an osmotic imbalance that disrupts the balance of ions in the plant (Arif et al., 2020). Environmental stress can also affect the availability and mobility of nutrients in the soil. ...
... Salinity impairs the development and production of wheat (Royo et al., 2003). Salinity stress causes both osmotic stress and ion toxicity which cause serious growth and yield reduction (Arif et al., 2020). Salinity alters the cellular ultrastructure, prevents photosynthesis from occurring, damages membrane structures, generates reactive oxygen species, and inhibits enzyme activity, among other consequences on crop development and productivity. ...
... A remarkable decrease in lettuce growth under NaCl conditions may be due to decreased cell development and growth by blocking of all the translocation, which normally takes place through conductive tissue vessels (Queiros et al., 2011). Retardation of plant development under NaCl stress might result from the negative impact of salt stress on different physiological processes including decreased photosynthesis, stomatal impedance to water flow, accumulation of ROS and nutrient and hormonal imbalances (Arif et al., 2020;Sofy et al., 2020b). Also, salinity stress induces many harmful effects on plant growth, photosynthetic pigments, oxidative biomarkers, osmolytes and antioxidant enzyme activities (Farouk et al., 2020;Sofy et al., 2020c). ...
Salinity is one of the most important abiotic stresses that significantly decreases the productivity of agricultural crops. Melatonin (MT) acts as an antioxidant and plays a vital role in overcoming oxidative damage. However, previous literature has not provided a clear understanding of the impact of MT on lettuce plants under salinity stress. So, we investigated the effect of exogenous MT at 0 μM, 50 μM, 100 μM and 150 μM on lettuce plants grown under salinity stress (0 mM NaCl, 50 mM NaCl and 100 mM NaCl) with respect to vegetative growth, photosynthetic pigments, relative water content (RWC), electrolyte leakage (EL), malondialdehyde (MDA), H 2 O 2 , O 2 •- and antioxidants enzymes. Results showed that NaCl stress significantly decreased vegetative growth, RWC and photosynthetic pigments and in contrast enhanced dry matter, EL, MDA, H 2 O 2 , O 2 •- , Na ⁺ , Cl-, peroxidase (POD), superoxide dismutase (SOD) and glutathione reductase (GR) of lettuce plants compared to non-salinized control. The results demonstrated that under salinity conditions, foliar applications of MT significantly alleviated the harmful effects of salinity and increased number of leaves, leaf area, fresh weight, chlorophyll (a), chlorophyll (b), total chlorophyll, carotenoids and RWC in comparison to untreated plants (control). Meanwhile, dry matter, MDA, H 2 O 2 , O 2 •- , Na ⁺ , Cl-, POD, SOD and GR were significantly decreased compared to untreated lettuce plants. In this respect, spraying MT at 150 μM ranked the first, then 100 μM, compared to the lower concentration (50 μM). In conclusion, MT application can be used to alleviate harmful effects of salinity stress.
... Na + , Cl − , SO 4 2− , and HCO 3 − are some common ions that are found in saline soil in a wide range of concentrations and proportions. The increasing influx of these ions into plant root cells with high osmotic stress prevents the uptake of other essential nutrients especially potassium, K + (Arif et al. 2020;Makhlouf et al. 2022). Osmotic pressure and ionic toxicity from salinity can also disrupt a variety of physiological processes, including carbohydrate metabolism, respiration, and photosynthesis (Abbasi et al. 2016). ...
Despite the saline soils of Bangladesh having high potassium (K) availability, the acquisition of K by rice (Oryza sativa L.) is unsatisfactory. The study was designed to quantify the performance of rice yield components, macro-nutrient uptake, K + / Na + ratio, and nutrient use efficiency under the influence of improved K fertilization in a salt-affected soil. The salt-tolerant Boro rice cultivar (BRRI-47) was tested with seven different K treatments (0, 20, 40, 60, 80, 100, and 120 kg K ha −1) with three replications followed by a complete randomized design (CRD). The results indicated that increasing K levels had a positive influence on most of the growth and yield parameters of rice except plant height, unfilled grain number, and 1000 grain weight. Application of 100 kg K ha −1 raised the grain yield by 49% over control and 19.13% over the present national recommended dose (40 kg K ha −1). Straw yield increased by 42% in treatment K 120 and 36% in treatment K 100 over control, respectively. The K + /Na + ratio in plants was observed to be higher when K was applied at higher rates. Additionally, the different K doses improved the nutrient (N, P, K, S) uptake and decreased the internal N and K use efficiencies of rice. It can be summarized that 100 kg ha −1 K fertilization could be effective to improve rice production and nutrient uptake in coastal saline soil of Bangladesh while maintaining a high K + /Na + ratio.
... Nanotechnology has the potential to boost crop productivity by increasing the tolerance of plants in the context of abiotic stress [30]. Through the modulation of many biological, biochemical, and molecular mechanisms, NPs have been proven in many research investigations that these are essential in enhancing plants' ability to withstand abiotic stressors ( Fig. 13.1). ...
Abiotic stress constitutes a significant factor that has a negative impact on plant growth and crop output. These factors cause significant crop yield losses in many regions of the world, exacerbating food scarcity. Recognizing the rising prevalence of different abiotic stresses as a result of both human and environmental factors , the scientific community is concerned about mitigating their impact in order to maximize crop yield potential under stressed environments. Many viable strategies are being investigated in an effort to improve plants' abiotic stress tolerance, and in recent years, nanotechnology has gained momentum to occupy a potential position to mitigate the limitations linked with abiotic stress in order to achieve a sustainable future for agriculture worldwide. They include the application of nanoparticles, which have been found to improve plant performance during stressful events. Nano-particles can be utilized to supply nutrients to plants, combat crop diseases and pathogens , as well as monitor trace minerals in soil by capturing their signals. The usage of nanoparticles in modern agriculture is very common since they are tiny, easily soluble , and effective for plant absorption. Several nanoparticles and their potential in protecting plants from a variety of abiotic stresses are explained in detail in this chapter.
Global climate change has a profound impact on plant growth and productivity, inducing a range of biotic and abiotic stresses. Among these, the most prominent abiotic stressors include salinity, drought, extreme temperatures, heavy metal contamination, etc. These stresses collectively result in significant reduction in crop yield across varied global regions, exacerbating food security challenges. To enhance plants’ resilience to abiotic stresses, extensive research is underway to explore promising techniques and strategies. Nanotechnology has emerged as a promising field, offering novel tools to enhance plant resilience against abiotic stresses. This abstract explores the molecular-level interactions between nanoparticles and plants under abiotic stress. In recent years, nanoparticles, particularly metallic and metal oxide nanoparticles, have gained attention for their ability to alleviate abiotic stress-induced damage in plants. These nanoparticles, due to their small size and high surface area, can be engineered to carry essential nutrients and antioxidants, enabling targeted delivery to plants. Furthermore, they can serve as catalytic agents, facilitating enzymatic processes involved in stress response and plant growth. At the molecular level, nanoparticles interact with plant cells through complex mechanisms, including ion uptake, enzyme regulation, and signal transduction pathways. For example, silver nanoparticles have been shown to modulate the expression of stress-responsive genes, enhancing the plant’s ability to combat drought stress. Titanium dioxide nanoparticles can act as ROS scavengers, reducing oxidative damage caused by salinity stress. Additionally, carbon-based nanoparticles can promote nutrient uptake and transport, alleviating deficiencies induced by heavy metal toxicity. Understanding the precise mechanisms of nanoparticle-plant interactions at the molecular level is crucial for designing tailored solutions to combat climate-induced abiotic stresses. By harnessing nanoparticles, we can develop innovative strategies to enhance crop resilience, improve yields, and ensure food security in the face of a changing climate. However, it is imperative to conduct comprehensive research on the safety and environmental impacts of nanoparticle applications in agriculture to ensure sustainable and responsible utilization.
A new book on abiotic plant stress physiology in the Arabic language contains 7 chapters as well as the introduction:
Chapter 1: Water Stress
Chapter 2: Salt Stress
Chapter 3: Heat Stress
Chapter 4: Heavy metals and minerals stress
Chapter 5: Ultraviolet Stress
Chapter 6: The effect of abiotic stress factors that occur before harvest on the ability to store and preserve produce.
Chapter 7: Magnetic Stress
References
Due to its readily soluble nature in groundwater and surface water, an excess accumulation of soluble salts in the soil, especially sodium chloride (NaCl), could pose serious threats to crop growth and development by disrupting physiological and biochemical processes in plants. The excess of soluble salt could originate from natural processes, such as weathering (physical or chemical) of parent rock materials, wind, and rainfall, and is thus termed as primary soil salinization. Besides, various anthropogenic activities, such as irrigation with brackish or saline water, poor land and water management, overuse of synthetic fertilizers, overextraction of groundwater, and saltwater intrusion into coastal aquifers as a result of sea level rise, could also create a salinity problem, which is known as secondary soil salinization. The salinity problem in soil and land of arid and semi-arid regions is even more severe. The concentration of salt is referred to as the sum of cation and anion or only cation or anion and is expressed as mg L−1. However, it is commonly measured as electrical conductivity (EC) of saturated soil extract (ECe) for scientific and analytical purposes and is expressed with a unit of decisiemens per meter (dS m−1). Salinity is a multi-dimensional stress for plants, impairing plant growth and development through cytotoxicity caused by excessive uptake of Na+ and Cl− ions, water stress, and nutritional imbalance. In addition, salinity is generally accompanied by oxidative stress because of the overproduction of reactive oxygen species. The water scarcity phase of salinity results in substantial yield loss through rapid inhibition of growth and development, while the ionic toxicity phase causes rapid leaf senescence through a variety of adverse impacts on cellular components simultaneously. Moreover, prooxidants generation at higher levels of salt stress threatens standard metabolic processes and poses a risk of irreversible damage on biomembranes, cellular organelles, nucleic acids, and proteins. Such constraints make cropping a great challenge in salt-affected areas; however, naturally salt-tolerant plants, also known as halophytes or semi-halophytes, can easily withstand comparatively higher salt concentrations because of their adaptive morpho-physiological and molecular mechanisms. Unlike halophytic or semi-halophytic plants, most of the commonly cultivated crops fail to tolerate salt stress as they fall under glycophyte or salt-susceptible category. However, the process of natural selection coupled with developing agricultural technologies has played a substantial role in imparting greater tolerance of crops to salt stress over the past few decades. Nevertheless, rapid sea level rise driven by anthropogenic climate change affecting the salinity of surface and groundwater in coastal areas and persistent spreading of salinity both in terms of land area and concentration call for a combined approach of compatible cultivar development and adoption of suitable management strategies. This necessitates a systematic and in-depth understanding of existing adaptations, tolerance mechanisms, and cultivation methods for stepping forward in strategizing future crop yield improvement programs. Therefore, the present review focuses on highlighting (i) the factors intensifying salinity problem in soils, (ii) salinity dynamics in plants including its uptake, transport, storage, and development of stress, (iii) salinity sensing mechanism in plants, (iv) naturally occurring adaptations, (v) genetic variabilities, and (vi) tolerance mechanisms available within cultivable crop germplasms with specific emphasis on morphological and anatomical tolerance, physiochemical tolerance, and role of genetic resources in enhancing tolerance against salinity. A number of agronomic, cultural, and technological management options to alleviate the adverse impacts of salt stress on crop plants are also discussed in this review, which could potentially offer invaluable information for the development of salt-tolerant crop improvement programs and optimized land and water management practices.
The excessive accumulation of sodium chloride (NaCl) in soil can result in soil salinity, which poses a significant challenge to plant growth and crop production due to impaired water and nutrient uptake. On the other hand, hydropriming (WP) and low level of NaCl priming can improve the germination of seeds, chlorophyll contents, oil and seed yield in plants. That’s why this study investigates the impact of hydro and different levels of NaCl (0.5, 1.0, 1.5 and 2.0%) priming, as pre-treatment techniques on canola seeds germination, growth and yield of two varieties Punjab and Faisal Canola. Results showed that, WP performed significant best for increase in germination (~ 20 and ~ 22%) and shoot length (~ 6 and ~ 10%) over non-priming (NP) in Punjab Canola and Faisal Canola respectively. A significant increase in plant height (~ 6 and ~ 7%), root length (~ 1 and ~ 7%), shoot fresh weight (~ 5 and ~ 7%), root fresh weight (~ 6 and ~ 7%) in Punjab Canola and Faisal Canola respectively. It was also observed that plants under WP and 0.5%NaCl priming were also better in production of seed yield per plant, oil contents, silique per plant, seeds per silique, and branches per plant chlorophyll contents and leaf relative water contents over NP. In conclusion, WP and 0.5%NaCl has potential to improve the germination, growth, yield and oil attributes of canola compared to non-priming, 1.0%NaCl priming, 1.5%NaCl priming and 2.0%NaCl priming.
Salinity stress poses a significant threat to crop productivity worldwide, necessitating effective mitigation strategies. This study investigated the phytochemical composition and potential of grape seed extract (GSE) to mitigate salinity stress effects on faba bean plants. GC–MS analysis revealed several bioactive components in GSE, predominantly fatty acids. GSE was rich in essential nutrients and possessed a high antioxidant capacity. After 14 days of germination, GSE was applied as a foliar spray at different concentrations (0, 2, 4, 6, and 8 g/L) to mitigate the negative effects of salt stress (150 mM NaCl) on faba bean plants. Foliar application of 2–8 g/L GSE significantly enhanced growth parameters such as shoot length, root length, fresh weight, and dry weight of salt-stressed bean plants compared to the control. The Fv/Fm ratio, indicating photosynthetic activity, also improved with GSE treatment under salinity stress compared to the control. GSE effectively alleviated the oxidative stress induced by salinity, reducing malondialdehyde, hydrogen peroxide, praline, and glycine betaine levels. Total soluble proteins, amino acids, and sugars were enhanced in GSE-treated, salt-stressed plants. GSE treatment under salinity stress modulated the total antioxidant capacity, antioxidant responses, and enzyme activities such as peroxidase, ascorbate peroxidase, and polyphenol oxidase compared to salt-stressed plants. Gene expression analysis revealed GSE (6 g/L) upregulated photosynthesis (chlorophyll a/b-binding protein of LHCII type 1-like (Lhcb1) and ribulose bisphosphate carboxylase large chain-like (RbcL)) and carbohydrate metabolism (cell wall invertase I (CWINV1) genes) while downregulating stress response genes (ornithine aminotransferase (OAT) and ethylene-responsive transcription factor 1 (ERF1)) in salt-stressed bean plants. The study demonstrates GSE’s usefulness in mitigating salinity stress effects on bean plants by modulating growth, physiology, and gene expression patterns, highlighting its potential as a natural approach to enhance salt tolerance.
Water scarcity is one of the most impactful emerging challenges around the globe,
enhancing the competition between domestic and agricultural usage. This scenario is
even worse in arid and semi-arid areas owing to the low availability of water resources.
The current research trial aimed to check the adaptability potential and leaf functioning
of Ziziphus mauritiana and Salvadora oleoides under water stress. A pot experiment was
conducted in the Forest Nursery and Experimental Area, Institute of Forest Sciences,
The Islamia University of Bahawalpur. The four levels of water scarcity i.e., 60% field
capacity (FC), 50% FC, 40% FC and 30% FC along with control were evaluated
following a complete randomized design (CRD). The outcomes exhibited that water
stress has a profound impact on the growth of both tree species. Water stress has reduced
the plant height (41% & 43%), stem diameter (6.47% & 4.17%), shoot fresh weight
(10.6% & 10.2%) and root fresh weight (40.21% & 44.07%) w.r.t control in Z.
mauritiana and S. oleoides respectively. A similar trend was observed in biochemical
parameters where the stress has induced higher enzymatic activities such as SOD (1.8 &
1.18 mg-1 protein), POD (5.81 & 2.79 mg-1 protein), CAT (1.93 & 0.68 mg-1 protein)
and MDA levels (0.039 & 0.034 mol g-1 FW) respectively. Moreover, the photosynthetic
pigments such as chlorophyll a, chlorophyll b, total chlorophyll and carotenoids also
exhibited antagonistic responses towards drought stress. The overall results showed that
Z. mauritiana performed better as compared to S. oleoides under drought stress. The
outcomes of the study provide meaningful insights regarding the plantation on marginal
lands in arid to semi-arid regions.
This chapter offers an overview of the mechanisms that underlie plant salt tolerance, while acknowledging their complexity and the resulting growth adaptations. It centers on the key components of plant salt tolerance strategies, including genetic modifications, the utilization of molecular genetics and insights from model plants, enhancing the understanding of these mechanisms. Efforts to engineer salt tolerance in crops are explored, taking into consideration the role of salt-tolerant relatives. Additionally, the examination includes the ecological, physiological, and growth impacts of salinity. Furthermore, the chapter delves into the intricacies of plant salt tolerance and the adaptive mechanisms that have evolved to alleviate salt-induced osmotic stress. It provides an analysis of the functions and distinctions of HKT1-type transporters in plants under salt stress, with a specific focus on the regulatory aspects of these transporters, including their role in sodium distribution and low-affinity Na+ transport. Agronomic management strategies for enhancing plant tolerance to salinity are extensively explored, and sustainable approaches aimed at optimizing crop resilience under salt stress conditions are discussed. Emphasis is placed on their significance in maintaining agricultural productivity while minimizing environmental consequences. Overall, this chapter serves as a valuable resource for understanding the molecular physiology of salt stress and the mechanisms of adaptation in high salt environments.
This chapter extensively explores the molecular mechanisms governing gene expression in plants facing abiotic stresses, with a specific focus on drought, salinity, extreme temperatures, and nutrient limitations. Recent advancements in molecular and genetic research have significantly enhanced the comprehension of plant stress responses. Plant hormones are highlighted as key regulators of gene expression and stress responses. Additionally, the involvement of reactive oxygen species (ROS) in signaling pathways and transcriptional networks is discussed. The chapter delves into the genetic and molecular mechanisms that modulate gene expression, thereby enhancing plant tolerance to abiotic stress. It underscores the importance of transcription factors and epigenetic regulation in plant responses to stress. In particular, it seeks to elucidate the roles of transcription factors, such as MYB, AP2/ERF, bHLH, and NAC. A deep understanding of these molecular mechanisms and regulatory networks is critical for future research aimed at unraveling the signaling pathways and gene regulatory networks that underpin plant responses to abiotic stress. The ultimate goal is to enhance crop stress tolerance and productivity under challenging environmental conditions.
Understanding and exploiting the intrinsic mechanisms of tolerance to multiple stresses in plants is the new frontier of sustainable agriculture, since environmental challenges often occur simultaneously in agricultural systems. We recently identified three fragments, named PS1-70, PS1-120 and G, in the scaffold of prosystemin, the protein precursor of tomato systemin. These protein fragments efficiently protect tomato plants against Botrytis cinerea and Spodoptera littoralis larvae attacks by inducing defence-related genes. Since it was previously demonstrated that prosystemin protects tomato plants also against soil salinity, we analyzed the ability of PS1-70, PS1-120 and G to confer salt tolerance. As expected, the application of 150 mM NaCl induced 24% reduction of shoot fresh weight. The treatment with PS1-70 and G induced 9% and 8% increase of shoot fresh weight. In addition, under salt stress, there is a significant increase in root biomass in treated plants suggesting that the treatment mitigated salt stress. Noteworthy, fragments application improved the growth of shoots, indicating a biostimulant activity on tomato growth. These data correlated with the upregulation of key stress-related genes, ( CAT2 , APX2 , and HSP90) , associated with the activation of antioxidant and free radical scavenging reactions in stressed plant cells. Our results add novel tools to the complex problem of sustainable crop protection against different environmental stresses.
The factorial experiment based on a randomized complete block design was conducted with three replications at the research greenhouse of Tabriz University in 2017. The experimental factors include three levels of salinity stress (non-saline, salinity 3 and 6 dS/m) from the source of sodium chloride, foliar spraying in three levels without hormonal and nutritional foliar spraying, foliar spraying of 2 mM silicon and foliar spraying of 1mM salicylic acid, and the third factor, bacterial inoculation in four levels included: no inoculation, inoculation with Azosprilium, inoculation with Azotobacter and combined inoculation of two bacteria. The results of this research showed that the salt stress reduced the growth and yield of garlic. Spraying of salicylic acid and silicon and inoculation with bacteria improved potassium absorption, plant height, and leaf surface area, number of leaves per plant, yield components, biomass, and yield of garlic. The treatments significantly reduced the sodium concentration in both roots and leaves. The positive effects of the proposed treatments not only improved plant growth and performance under salinity stress conditions but also under non-saline conditions. Among the studied treatments, salicylic acid and silicon foliar applications along with the combined use of Azospirillium and Azotobacter showed more favorable effects on the growth and productivity of garlic than the other treatments. Finally, it was suggested to use growth-promoting bacteria in combination with salicylic acid and silicon solution spraying to mitigate the effects of salinity stress in garlic plants.
The growth and productivity of crop plants are negatively affected by salinity-induced ionic and oxidative stresses. This study aimed to provide insight into the interaction of NaCl-induced salinity with Azolla aqueous extract (AAE) regarding growth, antioxidant balance, and stress-responsive genes expression in wheat seedlings. In a pot experiment, wheat kernels were primed for 21 h with either deionized water or 0.1% AAE. Water-primed seedlings received either tap water, 250 mM NaCl, AAE spray, or AAE spray + NaCl. The AAE-primed seedlings received either tap water or 250 mM NaCl. Salinity lowered growth rate, chlorophyll level, and protein and amino acids pool. However, carotenoids, stress indicators (EL, MDA, and H2O2), osmomodulators (sugars, and proline), antioxidant enzymes (CAT, POD, APX, and PPO), and the expression of some stress-responsive genes (POD, PPO and PAL, PCS, and TLP) were significantly increased. However, administering AAE contributed to increased growth, balanced leaf pigments and assimilation efficacy, diminished stress indicators, rebalanced osmomodulators and antioxidant enzymes, and down-regulation of stress-induced genes in NaCl-stressed plants, with priming surpassing spray in most cases. In conclusion, AAE can be used as a green approach for sustaining regular growth and metabolism and remodelling the physio-chemical status of wheat seedlings thriving in salt-affected soils.
Heat shock proteins (HSPs) are known to play a crucial role in the response of plants to environmental stress, particularly heat stress. Nevertheless, the function of HSPs in salt stress tolerance in plants, especially in barley, remains largely unexplored. Here, we aimed to investigate and compare the salt tolerance mechanisms between wild barley EC_S1 and cultivated barley RGT Planet through a comprehensive analysis of physiological parameters and transcriptomic profiles. Results demonstrated that the number of differentially expressed genes (DEGs) in EC_S1 was significantly higher than in RGT Planet, indicating that wild barley gene regulation is more adaptive to salt stress. KEGG enrichment analysis revealed that DEGs were mainly enriched in the processes of photosynthesis, plant hormone signal transduction, and reactive oxygen species metabolism. Furthermore, the application of weighted gene correlation network analysis (WGCNA) enabled the identification of a set of key genes, including small heat shock protein (sHSP), Calmodulin-like proteins (CML), and protein phosphatases 2C (PP2C). Subsequently, a novel sHSP gene, HvHSP16.9 encoding a protein of 16.9 kDa, was cloned from wild barley, and its role in plant response to salt stress was elucidated. In Arabidopsis, overexpression of HvHSP16.9 increased the salt tolerance. Meanwhile, barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) of HvHSP16.9 significantly reduced the salt tolerance in wild barley. Overall, this study offers a new theoretical framework for comprehending the tolerance and adaptation mechanisms of wild barley under salt stress. It provides valuable insights into the salt tolerance function of HSP, and identifies new candidate genes for enhancing cultivated barley varieties.
Increased soil salinization, tightly related to global warming and drought and exacerbated by intensified irrigation supply, implies highly detrimental effects on staple food crops such as wheat. The situation is particularly alarming for durum wheat (DW), better adapted to arid/semi-arid environments yet more sensitive to salt stress than bread wheat (BW). To enhance DW salinity tolerance, we resorted to chromosomally engineered materials with introgressions from allied halophytic Thinopyrum species. “Primary” recombinant lines (RLs), having portions of their 7AL arms distally replaced by 7el1L Th. ponticum segments, and “secondary” RLs, harboring Th. elongatum 7EL insertions “nested” into 7el1L segments, in addition to near-isogenic lines lacking any alien segment (CLs), cv. Om Rabia (OR) as salt tolerant control, and BW introgression lines with either most of 7el1 or the complete 7E chromosome substitution as additional CLs, were subjected to moderate (100 mM) and intense (200 mM) salt (NaCl) stress at early growth stages. The applied stress altered cell cycle progression, determining a general increase of cells in G1 and a reduction in S phase. Assessment of morpho-physiological and biochemical traits overall showed that the presence of Thinopyrum spp. segments was associated with considerably increased salinity tolerance versus its absence. For relative water content, Na⁺ accumulation and K⁺ retention in roots and leaves, oxidative stress indicators (malondialdehyde and hydrogen peroxide) and antioxidant enzyme activities, the observed differences between stressed and unstressed RLs versus CLs was of similar magnitude in “primary” and “secondary” types, suggesting that tolerance factors might reside in defined 7el1L shared portion(s). Nonetheless, the incremental contribution of 7EL segments emerged in various instances, greatly mitigating the effects of salt stress on root and leaf growth and on the quantity of photosynthetic pigments, boosting accumulation of compatible solutes and minimizing the decrease of a powerful antioxidant like ascorbate. The seemingly synergistic effect of 7el1L + 7EL segments/genes made “secondary” RLs able to often exceed cv. OR and equal or better perform than BW lines. Thus, transfer of a suite of genes from halophytic germplasm by use of fine chromosome engineering strategies may well be the way forward to enhance salinity tolerance of glycophytes, even the sensitive DW.
With increasing freshwater scarcity and greater use of seawater, fluctuating salinities are becoming common in water treatment systems. This can be challenging for salinity-sensitive processes like nitrification, especially in recirculating aquaculture systems (RAS), where maintaining nitrification efficiency is crucial for fish health. This study was undertaken to determine if prior exposure to seawater (priming) could improve nitrification in moving bed biofilm reactors (MBBR) under salinity increase from freshwater to seawater. The results showed that seawater-primed freshwater MBBRs had less than 10% reduction in nitrification activity and twice the ammonia oxidation capacity of the unprimed bioreactors after seawater transfer. The primed biofilms had different microbial community composition but the same nitrifying taxa, suggesting that priming promoted physiological adaptation of the nitrifiers. Priming may also have strengthened the extrapolymeric matrix protecting the nitrifiers. In MBBRs started up in brackish water (12‰ salinity), seawater priming had no significant impact on the nitrification activity and the microbial community composition. These bioreactors were inherently robust to salinity increase, likely because they were already primed to osmotic stress by virtue of their native salinity of 12‰. The results show that osmotic stress priming is an effective strategy for improving salinity acclimation in nitrifying biofilms and can be applied to water treatment systems where salinity variations are expected.
Considering the complex nature of salinity tolerance mechanisms, the use of isogenic lines or mutants possessing the same genetic background albeit different tolerance to salinity is a suitable method for reduction of analytical complexity to study these mechanisms. In the present study, whole transcriptome analysis was evaluated using RNA-seq method between a salt-tolerant mutant line “M4-73-30” and its wild-type “Zarjou” cultivar at seedling stage after six hours of exposure to salt stress (300 mM NaCl). Transcriptome sequencing yielded 20 million reads for each genotype. A total number of 7116 transcripts with differential expression were identified, 1586 and 1479 of which were obtained with significantly increased expression in the mutant and the wild-type, respectively. In addition, the families of WRKY, ERF, AP2/EREBP, NAC, CTR/DRE, AP2/ERF, MAD, MIKC, HSF, and bZIP were identified as the important transcription factors with specific expression in the mutant genotype. The RNA-seq results were confirmed at several time points using qRT-PCR for some important salt-responsive genes. In general, the results revealed that the mutant accumulated higher levels of sodium ion in the root and decreased its transfer to the shoot. Also, the mutant increased the amount of potassium ion leading to the maintenance a high ratio [K⁺]/[Na⁺] in the shoot compared to its wild-type via fast stomata closure and consequently transpiration reduction under the salt stress. Moreover, a reduction in photosynthesis and respiration was observed in the mutant, resulting in utilization of the stored energy and the carbon for maintaining the plant tissues, which is considered as a mechanism of salt tolerance in plants. Up-regulation of catalase, peroxidase, and ascorbate peroxidase genes has resulted in higher accumulation of H2O2 in the wild-type compared to the mutant. Therefore, the wild-type initiated rapid ROS signals which led to less oxidative scavenging in comparison with the mutant. The mutant increased expression in the ion transporters and the channels related to the salinity to maintain the ion homeostasis. In overall, the results demonstrated that the mutant responded better to the salt stress under both osmotic and ionic stress phases and lower damage was observed in the mutant compared to its wild-type under the salt stress.
Abstract: The aim of the present study is to review the structural characteristics possessed and the adaptations implemented by Suaeda vermiculata; a partially succulent habitat-indifferent desert halophyte, to cope with salinity and drought stresses and gaining insight into its tolerance mechanisms. These characteristics include succulence, leaf burns, leaf shedding, stunted growth habit, change in colour of the leaves, thick cuticular layers and sunken stomata. Deep rooting system and high root/shoot ratio are two more drought adaptations that may also be incorporated as tolerance mechanisms, but no previous studies were encountered for S. vermiculata. These adaptations allowed S. vermiculata to tolerate broad distribution in arid and semi-arid regions and variable habitats including salinity. The presence of small glossy seeds devoid of structures enhancing dispersal, limit its range of spatial dispersal and may be regarded as an inherent limit to tolerance mechanisms.
The aim of the present study is to review the structural characteristics possessed and the adaptations implemented by Suaeda vermiculata; a partially succulent habitat-indifferent desert halophyte, to cope with salinity and drought stresses and gaining insight into its tolerance mechanisms. These characteristics include succulence, leaf burns, leaf shedding, stunted growth habit, change in colour of the leaves, thick cuticular layers and sunken stomata. Deep rooting system and high root/shoot ratio are two more drought adaptations that may also be incorporated as tolerance mechanisms, but no previous studies were encountered for S. vermiculata. These adaptations allowed S. vermiculata to tolerate broad distribution in arid and semi-arid regions and variable habitats including salinity. The presence of small glossy seeds devoid of structures enhancing dispersal, limit its range of spatial dispersal and may be regarded as an inherent limit to tolerance mechanisms.
Plant resistance to salinity stress is one of the main challenges of agriculture. The comprehension of the molecular and cellular mechanisms involved in plant tolerance to salinity can help to contrast crop losses due to high salt conditions in soil. In this study, Salicornia brachiata and Suaeda maritima, two plants with capacity to adapt to high salinity levels, were investigated at proteome level to highlight the key processes involved in their tolerance to NaCl. With this purpose, plants were treated with 200 mM NaCl as optimal concentration and 500 mM NaCl as a moderate stressing concentration for 14 days. Indeed, 200 mM NaCl did not result in an evident stress condition for both species, although photosynthesis was affected (with a general up accumulation of photosynthesis-related proteins in S. brachiata under salinity). Our findings indicate a coordinated response to salinity in both the halophytes considered, under NaCl conditions. In addition to photosynthesis, heat shock proteins and peroxidase, expansins, signaling processes, and modulation of transcription/translation were affected by salinity. Interestingly, our results suggested distinct mechanisms of tolerance to salinity between the two species considered, with S. brachiata likely having a more efficient mechanism of response to NaCl.
The fresh water constitute only 3% of the total water on earth out of which underground water constitute 29 and <1% is in the form of lakes and rivers on the earth surface. Considering the rapidly increasing human population and demand for diverse food items crop production must increase substantially. At the same time arable land and good quality irrigation water resources are being depleted at faster rate particularly in the arid, semi-arid and tropical regions. Over the years the salinization of soil and water has steadily increased due to various causes and the increase in food production has essentially depends on this degrading resources. Since the balance between water demand and water availability has reached critical level in many regions of the world a sustainable approach to water resources and salinity management has become imperative. This chapter highlights global water resources, its demand and supply, salinity and its causes, effect of climate change and its management for sustainable use
(PDF) Water Demand and Salinity. Available from: https://www.researchgate.net/publication/339064236_Water_Demand_and_Salinity [accessed Mar 26 2020].
Soil salinity is one of the main abiotic constraints limiting plant growth. This paper focuses on the concept of internal adaptation in relation to salt tolerance during the vegetative phase. Under saline conditions, we evaluated some anatomical changes in stems (area, perimeter, cortex thickness, stele area, stele perimeter, pith area) and roots (thickness, cortex thickness and stele thickness) of two acacia species (A. karroo and A. saligna). Plants of 90 days old were cultured at various concentrations of NaCl (0, 200, 400 and 600 mM) for 21 days. The experiment was laid out in completely randomized design with four replications. For microscopic analysis, the stem tissues were cross-sectioned and the root were profile viewing. Results showed that salt caused remarkable changes in some anatomical-related parameters. Microscopic studies showed that every acacia species had made its own anatomical changes in stem and root by increasing/decreasing organ area, such as cortex thickness, stele thickness and pith area compared to control. In conclusion, under saline regimes, both species adapted specific characteristics of the roots and stems for better survival under saline environments.
Brassinosteroids (BRs) are a group of polyhydroxylated plant steroid hormones crucial for many aspects of plant life. BRs were originally characterized for their function in cell elongation, but it is becoming clear that they play major roles in plant growth, development and responses to several stresses such as temperature and drought. A BR signaling pathway from cell surface receptors to central transcription factors has been well characterized. Here we summarize recent progress towards understanding the BR pathway including BR perception and the molecular mechanisms of BR signaling. Next, we discuss the roles of BRs in development and stress responses. Finally, we show how knowledge of the BR pathway is being applied to manipulate the growth and stress responses in crops. These studies highlight the complex regulation of BR signaling, multiple points of crosstalk between BRs and other hormones or stress responses, and finely tuned spatiotemporal regulation of BR signaling.
Kandelia candel is one of the mangrove species that are most resistant to environmental stress. As a typical nonsalt-secreting mangrove plant, K. candel is an ideal biological material to analyze the molecular mechanism of salt tolerance in woody plants. In this study, changes in protein abundance and expression profile in K. candel roots under high-salinity stress of 600 mmol L-1 NaCl were analyzed using isobaric tags for relative and absolute quantification (iTRAQ) assay. Moreover, the physiological parameters associated with metabolic pathways in which the differentially abundant proteins (DAPs) are involved were determined. A total of 5577 proteins were identified by iTRAQ analysis of the K. candel root proteins, of which 227 were DAPs with a fold change ratio >1.2 or a fold change ratio <0.83 and a P-value <0.05. A total of 227 DAPs consisting of 110 up-regulated and 117 down-regulated proteins were identified. Our Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the DAPs were primarily involved in biological processes including carbohydrate and energy metabolisms, stress response and defense, cell wall structure, and secondary metabolism. The results of the physiological parameters showed that their profile changes were consistent with those of the proteome analysis. The results of the proteome and physiological parameters showed that K. candel roots could resist high-salinity stress by maintaining a normal Embden-Meyerhof-Parnas and tricarboxylic acid (EMP-TCA) pathway, increasing the activities of various antioxidant enzymes and antioxidant contents, stabilizing the cell wall structure, and accumulating secondary metabolites such as triterpenoids.
Background:
Photosynthetic efficiency might be a key factor determining plant resistance to abiotic stresses. Plants can sense when growing conditions are not favorable and trigger an internal response at an early stage before showing external symptoms. When a high amount of salt enters the plant cell, the membrane system and function of thylakoids in chloroplasts could be destroyed and affect photosynthetic performance if the salt concentration is not regulated to optimal values. Oryza species have salt-tolerant and salt-sensitive genotypes; however, very few studies have investigated the genetic architecture responsible for photosynthetic efficiency under salinity stress in cultivated rice.
Results:
We used an imaging-based chlorophyll fluorometer to monitor eight rice varieties that showed different salt tolerance levels for four consecutive days under control and salt conditions. An analysis of the changes in chlorophyll fluorescence parameters clearly showed the maximum quantum efficiency of PSII in sensitive varieties was significantly reduced after NaCl treatment when compared to tolerant varieties. A panel of 232 diverse rice accessions was then analyzed for chlorophyll fluorescence under salt conditions, the results showed that chlorophyll fluorescence parameters such as F0 and NPQ were higher in Japonica subspecies, ΦPSII of Indica varieties was higher than that in other subgroups, which suggested that the variation in photosynthetic efficiency was extensively regulated under salt treatment in diverse cultivated rice. Two significant regions on chromosome 5 were identified to associate with the fraction of open PSII centers (qL) and the minimum chlorophyll fluorescence (F0). These regions harbored genes related to senescence, chloroplast biogenesis and response to salt stress are of interest for future functional characterization to determine their roles in regulating photosynthesis.
Conclusions:
Rice plant is very sensitive to salinity stress, especially at young seedling stage. Our work identified the distribution pattern of chlorophyll fluorescence parameters in seedlings leaf and their correlations with salt tolerance level in a diverse gene pool. We also revealed the complexity of the genetic architecture regulating rice seedling photosynthetic performance under salinity stress, the germplasm analyzed in this study and the associated genetic information could be utilized in rice breeding program.
The halophyte Suaeda salsa displayed strong resistance to salinity. Up to date, molecular mechanisms underlying tolerance of S. salsa to salinity have not been well understood. In the present study, S. salsa seedlings were treated with 30‰ salinity and then leaves and roots were subjected to Illumina sequencing. Compared with the control, 68,599 and 77,250 unigenes were significantly differentially expressed in leaves and roots in saline treatment, respectively. KEGG enrichment analyses indicated that photosynthesis process, carbohydrate, lipid and amino acid metabolisms were all downregulated in saline treatment, which should inhibit growth of S. salsa. Expression levels of Na+/H+ exchanger, V-H+ ATPase, choline monooxygenase, potassium and chloride channels were upregulated in saline treatment, which could relieve reduce over-accumulation of Na+ and Cl-. Fe-SOD, glutathione, L-ascorbate and flavonoids function as antioxidants in plants. Genes in relation to them were all upregulated, suggesting that S. salsa initiated various antioxidant mechanisms to tolerate high salinity. Besides, plant hormones, especially auxin, ethylene and jasmonic acid signaling transduction pathways were all upregulated in response to saline treatment, which were important to gene regulations of ion transportation and antioxidation. These changes might comprehensively contribute to tolerance of S. salsa to salinity. Overall, the present study provided new insights to understand the mechanisms underlying tolerance to salinity in halophytes.
University of California at Berkeley I or UCB-1 pistachio rootstock is propagated from the cross between Pistacia integerrima male × Pistacia atlantica female. So far, no report has been presented on the proteomic profile of Pistacia genus. In this research, 7-month-old UCB-1 rootstocks that were produced by tissue culture method and grown in pots containing 1/3 perlite, 1/3 clay and 1/3 sand were exposed to the three different concentrations of NaCl including 0, 100 and 200 mM for 30 days in the controlled conditions in the greenhouse. In the first step, under these three different concentrations of NaCl, the content of malondialdehyde and activities of guaiacol peroxidase, superoxide dismutase, catalase and peroxidase were evaluated. Malondialdehyde content increased up to 100 mM NaCl and then decreased. Activities of guaiacol peroxidase, superoxide dismutase and catalase increased with increasing concentration of NaCl, while peroxidase activity reduced. In the second step, 0 and 100 mM NaCl were selected to evaluate changes in the proteomic profile of this rootstock using MALDI-TOF/TOF method. In this study, ribonucleoside-diphosphate reductase small chain, polcalcin Phl p 7-like and golgin subfamily A member 5 were identified for the first time in response to salinity stress and have not been previously reported to be involved in the response of plant under abiotic stresses. Moreover, in this study, five unknown proteins were identified in UCB-1 pistachio under salinity stress.
Salt stress is one of the major adverse environmental factors limiting crop productivity. Considering Iran as one of the bread wheat origins, we sequenced root transcriptome of an Iranian salt tolerant cultivar, Arg, under salt stress to extend our knowledge of the molecular basis of salinity tolerance in Triticum aestivum. RNA sequencing resulted in more than 113 million reads and about 104013 genes were obtained, among which 26171 novel transcripts were identified. A comparison of abundances showed that 5128 genes were differentially expressed due to salt stress. The differentially expressed genes (DEGs) were annotated with Gene Ontology terms, and the key pathways were identified using Kyoto Encyclopedia of Gene and Genomes (KEGG) pathway mapping. The DEGs could be classified into 227 KEGG pathways among which transporters, phenylpropanoid biosynthesis, transcription factors, glycosyltransferases, glutathione metabolism and plant hormone signal transduction represented the most significant pathways. Furthermore, the expression pattern of nine genes involved in salt stress response was compared between the salt tolerant (Arg) and susceptible (Moghan3) cultivars. A panel of novel genes and transcripts is found in this research to be differentially expressed under salinity in Arg cultivar and a model is proposed for salt stress response in this salt tolerant cultivar of wheat employing the DEGs. The achieved results can be beneficial for better understanding and improvement of salt tolerance in wheat. © 2019 Amirbakhtiar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Key message
Mitigation of deleterious effects of salinity promoted by exogenous proline can be partially explained by changes in proline enzymatic metabolism and expression of specific proline-related genes.
Abstract
Proline accumulation is a usual response to salinity. We studied the ability of exogenous proline to mitigate the salt harmful effects in sorghum (Sorghum bicolor) leaves. Ten-day-old plants were cultivated in Hoagland’s nutrient solution in either the absence or presence of salinity (NaCl at 75 mM) and sprayed with distilled water or 30 mM proline solution. Salinity deleterious effects were alleviated by exogenous proline 14 days after treatment, with a return in growth and recovery of leaf area and photosynthetic parameters. Part of the salinity response reflected an improvement in ionic homeostasis, provided by reduction in Na⁺ and Cl⁻ ions and increases in K⁺ and Ca²⁺ ions as well as increases of compatible solutes. In addition, the application of proline decreased membrane damage and did not increase relative water content. Proline-treated salt-stressed plants displayed increase in proline content, a response counterbalanced by punctual modulation in proline synthesis (down-regulation of Δ¹-pyrroline-5-carboxylate synthetase activity) and degradation (up-regulation of proline dehydrogenase activity) enzymes. These responses were correlated with expression of specific proline-related genes (p5cs1 and prodh). Our findings clearly show that proline treatment results in favorable changes, reducing salt-induced damage and improving salt acclimation in sorghum plants.
Salinity is a major threat to modern agriculture causing inhibition and impairment of crop growth and development. Here, we not only review recent advances in salinity stress research in plants but also revisit some basic perennial questions that still remain unanswered. In this review, we analyze the physiological, biochemical, and molecular aspects of Na⁺ and Cl⁻ uptake, sequestration, and transport associated with salinity. We discuss the role and importance of symplastic versus apoplastic pathways for ion uptake and critically evaluate the role of different types of membrane transporters in Na⁺ and Cl⁻ uptake and intercellular and intracellular ion distribution. Our incomplete knowledge regarding possible mechanisms of salinity sensing by plants is evaluated. Furthermore, a critical evaluation of the mechanisms of ion toxicity leads us to believe that, in contrast to currently held ideas, toxicity only plays a minor role in the cytosol and may be more prevalent in the vacuole. Lastly, the multiple roles of K⁺ in plant salinity stress are discussed.
Key message
Sustaining yield gains of grain legume crops under growing salt-stressed conditions demands a thorough understanding of plant salinity response and more efficient breeding techniques that effectively integrate modern omics knowledge.
Abstract
Grain legume crops are important to global food security being an affordable source of dietary protein and essential mineral nutrients to human population, especially in the developing countries. The global productivity of grain legume crops is severely challenged by the salinity stress particularly in the face of changing climates coupled with injudicious use of irrigation water and improper agricultural land management. Plants adapt to sustain under salinity-challenged conditions through evoking complex molecular mechanisms. Elucidating the underlying complex mechanisms remains pivotal to our knowledge about plant salinity response. Improving salinity tolerance of plants demand enriching cultivated gene pool of grain legume crops through capitalizing on ‘adaptive traits’ that contribute to salinity stress tolerance. Here, we review the current progress in understanding the genetic makeup of salinity tolerance and highlight the role of germplasm resources and omics advances in improving salt tolerance of grain legumes. In parallel, scope of next generation phenotyping platforms that efficiently bridge the phenotyping–genotyping gap and latest research advances including epigenetics is also discussed in context to salt stress tolerance. Breeding salt-tolerant cultivars of grain legumes will require an integrated “omics-assisted” approach enabling accelerated improvement of salt-tolerance traits in crop breeding programs.
Extracts of the brown alga, Ascophyllum nodosum, are widely used as plant biostimulants to improve growth and to impart tolerance against abiotic stresses. However, the molecular mechanisms by which A. nodosum extract (ANE) mediates stress tolerance are still largely unknown. The aim of this study was to study selected anti-stress mechanisms at the transcriptome level. We show that methanolic sub-fractions of ANE improved growth of Arabidopsis thaliana under NaCl stress; biomass increased by approximately 50% under 100 mM and 150 mM NaCl, relative to the control. Bioassay-guided fractionation revealed that the ethyl acetate sub-fraction of ANE (EAA) had the majority of stress alleviating, bioactive components. Microarray analysis showed that EAA elicited substantial changes in the global transcriptome on day 1 and day 5, after treatment. On day one, 184 genes were up-regulated while this number increased to 257 genes on day 5. On the other hand, 91 and 262 genes were down-regulated on day 1 and day 5, respectively. On day 1, 2.2% of the genes altered were abiotic stress regulated and this increased to 6% on day 5. EAA modulate the expression of number of the genes involved in stress responses, carbohydrate metabolism, and phenylpropanoid metabolism. Thus, our results suggested that bioactive components in the ethyl acetate fraction of A. nodosum induced salinity tolerance in A. thaliana by modulating the expression of a plethora of stress-responsive genes, providing a better understanding of the mechanisms through which ANE mediates tolerance by plants to salinity stress.
Background:
The res (restored cell structure by salinity) mutant, recently identified as the first tomato mutant accumulating jasmonate in roots under non-stressful conditions, exhibits a remarkable growth inhibition and morphological alterations in roots and leaves, which are suppressed when the mutant plants are exposed to salinity. In order to understand the molecular basis of the phenotype recovery induced by salt stress in the res mutant, we carried out a comparative transcriptomic analysis in roots and leaves of wild-type and res plants in absence of stress (control) and when the phenotypic recovery of res mutant began to be observed upon salt stress (5 days of 200 mM NaCl).
Results:
The number of differentially expressed genes was three times greater in roots than in leaves of res vs WT plants grown in control, and included the down-regulation of growth-promoting genes and the up-regulation of genes involved in Ca2+ signalling, transcription factors and others related to stress responses. However, these expression differences were attenuated under salt stress, coinciding with the phenotypic normalisation of the mutant. Contrarily to the attenuated response observed in roots, an enhanced response was found in leaves under salt stress. This included drastic expression changes in several circadian clock genes, such as GIGANTEA1, which was down-regulated in res vs WT plants. Moreover, the higher photosynthetic efficiency of res leaves under salt stress was accompanied by specific salt-upregulation of the genes RUBISCO ACTIVASE1 and ALTERNATIVE OXIDASE1A. Very few genes were found to be differentially expressed in both tissues (root and leaf) and conditions (control and salt), but this group included SlWRKY39 and SlMYB14 transcription factors, as well as genes related to protein homeostasis, especially protease inhibitors such as METALLOCARBOXYPEPTIDASE INHIBITOR, which also seem to play a role in the phenotype recovery and salt tolerance of res mutant.
Conclusions:
In summary, in this study we have identified genes which seem to have a prominent role in salt tolerance. Moreover, we think this work could contribute to future breeding of tomato crops with increased stress tolerance.
Plant growth and productivity are affected by both biotic and abiotic stress factors. Among the abiotic stresses, salt stress is the most prevalent and deleterious environmental factor which limits crop yield globally. Combined with the increasing population and food demands, this poses a great challenge to humanity. Currently, salinity affects more than 20% of the irrigated land. This is estimated to increase drastically in the near future due to the excessive irrigation practices. These factors have necessitated the researchers to understand the salt tolerance mechanisms in plants in order to use various approaches to generate salt-tolerant crops. Due to their sessile nature, plants cannot evade the stressful environment, and therefore, some species have evolved various adaptive strategies to grow and reproduce under unfavorable environments. Salt stress imparts both osmotic and ionic stress to the plants, affecting their metabolism and ion homeostasis, thereby leading to reduced growth and productivity and death in some cases. Salt tolerance is a complex phenomenon involving changes in the biochemical, molecular, and physiological processes of the plant. These changes consisting of a readjustment in the genomic and proteomic complement of the plants are imperative in unraveling the tolerance mechanisms. Recent advances in the omics research have shed more light on a range of promising candidate genes and proteins that render salt tolerance to plants. In this chapter, we describe the general effects of salt stress, the tolerance mechanisms of plants, and how recent advances in the field of proteomics can be utilized to enhance salt tolerance of crop plants.
In the post-genomic era, increasing efforts have been done to describe the relationship between genome and phenotype in plants. It has become clear that even a complete understanding of the state of the genes, messages, and proteins in a living system does not reveal its phenotype. Metabolites are the main readouts of gene vs environment interactions and represents the sum of all the levels of regulation in between gene to enzyme. Therefore, metabolome can be considered as the final recipient of biological information flow. Some metabolites have a very short lifetime and are indicators of specific metabolic reaction and of plant status. Indeed, it is well known that many of them are transformed during specific stresses and involved in plant stress response and resistance.
Salinity provides an important example of the effectiveness of metabolic changes in response to stress. In fact, exposure to salinity triggers specific strategies for cell osmotic adjustment and control of ion and water homeostasis to minimize stress damage and to re-establish growth. A ubiquitous mechanism that plants have evolved to adapt to salinity involves sodium sequestration in the vacuole, as a cheap osmoticum, and synthesis and accumulation of compatible compounds, both for osmotic adjustment and oxidative stress protection in the cytosol.
Metabolomics has been utilized for the study of plants in response to salinity stress in order to dissect particular patterns associated to stress tolerance. These studies have proved that certain metabolites are present in case of salt induced metabolic dysfunction and can act as effectors of osmotic readjustment or antioxidant response. Thus, the presence of particular metabolite patterns can be associated to stress tolerance and could serve as accurate markers for salt tolerant crop selection in breeding programs.
The impact of arbuscular mycorrhizal fungi (AMF) Glomus. tortuosum on morphology, photosynthetic pigments, chlorophyll (Chl) fluorescence, photosynthetic capacity and rubisco activity of maize under saline stress were detected under potted culture experiments. The experimental result indicated the saline stress notably reduced both dry mass and leaf area in contrast with the control treatment. Nevertheless, AMF remarkably ameliorated dry mass and leaf area under saline stress environment. Besides, maize plants appeared to have high dependency on AMF which improved physiological mechanisms by raising chlorophyll content, efficiency of light energy utilization, gas exchange and rubisco activity under salinity stress. In conclusion, AM could mitigate the growth limitations caused by salinity stress, and hence play a very important role in promoting photosynthetic capacity under salt stress in maize.
Soil salinization represents one of the major limiting factors of future increase crop production through the expansion or maintaining of cultivation area in the future. High salt levels in soils or irrigation water represent major environmental concerns for agriculture in semi-arid and arid zones. Recent advances in research provide great opportunities to develop effective strategies to improve crop salt tolerance and yield in different environments affected by the soil salinity. It was clearly demonstrated that plants employ both the common adaptive responses and the specific reactions to salt stress. The review of research results presented here may be helpful to understand the physiological, metabolic, developmental and other reactions of crop plants to salinity, resulting in the decrease of biomass production and yield. In addition, the chapter provides an overview of modern studies on how to mitigate salt stress effects on photosynthetic apparatus and productivity of crop plants with the help of phytohormones, glycinebetaine, proline, polyamines, paclobutrazol, trace elements and nanoparticles. To understand well these effects and to discover new ways to improve productivity in salinity stress conditions it is necessary to utilize efficiently possibilities of promising techniques and approaches focused on improvement of photosynthetic traits and photosynthetic capacity, which determines yield under salt stress conditions.
Salinity is a major constraint for intrinsically salt sensitive grain legume chickpea. Chickpea exhibits large genetic variation amongst cultivars, which show better yields in saline conditions but still need to be improved further for sustainable crop production. Based on previous multi-location physiological screening, JG 11 (salt tolerant) and ICCV 2 (salt sensitive) were subjected to salt stress to evaluate their physiological and transcriptional responses. A total of ~480 million RNA-Seq reads were sequenced from root tissues which resulted in identification of 3,053 differentially expressed genes (DEGs) in response to salt stress. Reproductive stage shows high number of DEGs suggesting major transcriptional reorganization in response to salt to enable tolerance. Importantly, cationic peroxidase, Aspartic ase, NRT1/PTR, phosphatidylinositol phosphate kinase, DREB1E and ERF genes were significantly up-regulated in tolerant genotype. In addition, we identified a suite of important genes involved in cell wall modification and root morphogenesis such as dirigent proteins, expansin and casparian strip membrane proteins that could potentially confer salt tolerance. Further, phytohormonal cross-talk between ERF and PIN-FORMED genes which modulate the root growth was observed. The gene set enrichment analysis and functional annotation of these genes suggests they may be utilised as potential candidates for improving chickpea salt tolerance.
HIGHLIGHTS: Major environmental and genetic factors determining stress-related protein abundance are discussed.
Major aspects of protein biological function including protein isoforms and PTMs, cellular localization and protein interactions are discussed.
Functional diversity of protein isoforms and PTMs is discussed.
Abiotic stresses reveal profound impacts on plant proteomes including alterations in protein relative abundance, cellular localization, post-transcriptional and post-translational modifications (PTMs), protein interactions with other protein partners, and, finally, protein biological functions. The main aim of the present review is to discuss the major factors determining stress-related protein accumulation and their final biological functions. A dynamics of stress response including stress acclimation to altered ambient conditions and recovery after the stress treatment is discussed. The results of proteomic studies aimed at a comparison of stress response in plant genotypes differing in stress adaptability reveal constitutively enhanced levels of several stress-related proteins (protective proteins, chaperones, ROS scavenging- and detoxification-related enzymes) in the tolerant genotypes with respect to the susceptible ones. Tolerant genotypes can efficiently adjust energy metabolism to enhanced needs during stress acclimation. Stress tolerance vs. stress susceptibility are relative terms which can reflect different stress-coping strategies depending on the given stress treatment. The role of differential protein isoforms and PTMs with respect to their biological functions in different physiological constraints (cellular compartments and interacting partners) is discussed. The importance of protein functional studies following high-throughput proteome analyses is presented in a broader context of plant biology. In summary, the manuscript tries to provide an overview of the major factors which have to be considered when interpreting data from proteomic studies on stress-treated plants.
Application of salt stress (100 mM) through root growing medium caused a considerable decrease in plant fresh and dry biomass, maximum quantum yield (Fv/Fm), chlorophyll contents, leaf water potential, and leaf Ca, K, P and N concentrations of two maize cultivars (Apex 836 and DK 5783). However, salt-induced increase was observed in leaf osmolality (LO), proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), Na⁺ concentration and activities of enzymatic antioxidants, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). Of five humic acid (HA) levels used under non-stress and stress conditions in an initial experiment, 100 mg L⁻¹ was chosen for subsequent studies. Exogenous application of humic acid (HA) at the rate of 100 mM as a foliar or pre-sowing seed treatment significantly increased the plant biomass, Fv/Fm, chlorophyll pigments and proline contents, while it considerably reduced the leaf water potential, H2O2 and MDA contents as well as the activities of all the afore-mentioned enzymatic antioxidants. Of both modes of exogenous treatment, foliar spray was better in improving plant biomass, chlorophyll contents, LO, leaf Na+ as well as the accumulation of all nutrients measured, however, in contrast, seed pre-treatment was more effective in altering leaf proline, H2O2 and MDA contents. Of both maize cultivars, cv. DK 5783 excelled in plant biomass, chlorophyll contents and leaf N, Ca and K concentrations as well as in the activities of all three antioxidant enzymes, whereas cv. Apex 836 was superior in leaf Na+ and P concentrations, H2O2 and MDA contents. Cv. DK 5783 was comparatively better in salt tolerance as compared to cv. Apex 836. Overall, exogenous application of HA was effective in improving salinity tolerance of maize plants which can be attributed to HA-induced increase in plant biomass, chlorophyll contents, mineral nutrients and activities of key antioxidant enzymes.
Increased salinity affects plants by toxic ion effects and by lowering soil water potential, which makes it difficult for plants to take up water. Salt marshes in Kansas are characterized by highly saline soils, but interspecific variation of photosynthesis and water potential in inland salt marsh species has been largely unexplored. Comparisons between species can help give a better understanding of how saline environments are tolerated by different plants. It was hypothesized that non-native Tamarix ramosissima has a greater tolerance to high salinity by maintaining lower water potential compared to the native species Spartina pectinata and Distichlis spicata. In this study, all three species were grown under controlled salinity treatments in a greenhouse experiment to determine if photosynthesis or water potential differ between species. Individuals of T. ramosissima, S. pectinata, and D. spicata were grown in 0, 15, or 30 g L⁻¹ salinity under greenhouse conditions for two weeks. Photosynthesis was reduced in all species under high salinity and stomates were particularly sensitive to increasing salinity in T. ramosissima. Individuals of non-native T. ramosissima were able to lower water potential to a greater extent than native D. spicata and S. pectinata. There is physiological tolerance to high salinity in all species, helping them to survive in conditions of Kansas salt marshes.
Due to sessile nature of plants, they face a variety of biotic and abiotic stresses during their life cycle. These stresses are responsible for disturbed cellular processes that adversely affect their growth and yield. To cope with these stresses, plants have developed various physiological mechanisms at cellular level that result in a change in morphology and help them to tolerate these environmental changes and respond to these changes with an optimal response. These responses of plants toward environmental stresses are both dynamic and complex that help them complete their life cycle rapidly under these stressful environmental conditions. The defense response of the plants to these stresses starts through variations in different molecular events with the involvement of different signaling molecules including the phytohormones. Phytohormones are small low-molecular-weight endogenous molecules that play important roles in different defense responses of plants against biotic as well as abiotic stresses. Along with their role in defense signaling, they also regulate various physiological, growth, and developmental processes in plants. These phytohormones include the auxins, cytokinins (CKs), gibberellins (GAs), ethylene (ET), jasmonic acid (JA), abscisic acid (ABA), salicylic acid (SA), and brassinosteroids (BRs) tocotrienols, triacontanols, and polyamines which are important ones that have ability to help plants to respond to different environmental stresses through their specific signaling properties. These signaling defense responses are the results of the interaction of various genes, helping the phytohormones to be involved in almost all cellular metabolic processes due to their specific modulations in the activities of these genes. All these phytohormones have their specific roles, e.g., auxin is involved in the regulation of differentiation and plant growth, cytokinin is responsible for cell division, gibberellin is responsible for stem elongation, seed germination, dormancy, senescence, and flower development, ethylene is involved in fruit ripening, and ABA has stress tolerance ability. The stress tolerance mechanism of plant is much complex that also has the involvement of other phytohormones, including the brassinosteroids (BRs), jasmonic acid (JA), salicylic acid (SA), polyamines (spermine, spermidine, putrescine, and thermospermine), tocotrienols, triacontanols (TRAI) as newly discovered ones. All the phytohormones help plants to survive under adverse environmental conditions with their specific roles in various growth, developmental, and physiological processes either through their endogenous accumulation or by exogenous application (foliar spray or seed priming) where the optimal concentration for the stress response is not sufficient. The exogenous use of these phytohormones has been increasing in crop plants with their economic value for obtaining the desired characters along with better production. The information given in the chapter will be helpful for plant growers and researchers to understand the mechanism of action of these phytohormones for better growth and production under changing environmental conditions.
Plant hormones play a vital role in promoting growth, development and metabolism of the plant, as well as act as a protector against various environmental stresses. In particular, salicylic acid (SA) is a potent phenolic signaling biomolecule and a multifaceted plant growth regulator which participates in a wide range of growth, metabolism and defense systems. Exogenous application of SA facilitates seed germination, growth, and flowering, up-regulates photosynthesis and increases the activity of enzymatic and non-enzymatic antioxidants. SA is a potent tool for sustainably mitigating environmental stresses in many plants by modulating physiological and metabolic processes of plants. Based on recent reports, SA biosynthesis and its regulation are discussed. This review highlights oxidative post-translational modifications, involvement of various proteins, and ROS interaction during SA signaling. Furthermore, it evaluates the role of exogenous application of SA in regulating diverse physiological and biochemical processes in healthy and stressed plants and assesses SA effects in plants exposed to various abiotic stress. Additionally, the cross talk of SA with other phytohormones and polyamines under normal and stressed conditions is also discussed.
Soil salinity is a major threat to agricultural sustainability and a global food security. Until now, most research has concentrated around stomatal limitation to photosynthesis, while non-stomatal limitations receiving much less attention. This work summarizes the current knowledge of impact of salinity on chloroplast metabolism and operation and finding viable solutions to minimize it. The major topics covered are: (1) the key targets of the photosynthetic apparatus under salt stress; (2) a tolerance of PSII to salt stress and its repair; (3) salinity effects on biochemistry of CO2 fixation and its regulation; (4) ionic requirements for optimal operation of chloroplasts; and (5) ion transport systems in chloroplasts that optimize chloroplast performance under hostile saline conditions. We show that enhancing plant capacity for protection by modifying PSI cyclic electron transport, redistribution of electron transport between photosystems, thylakoid membrane composition and photosynthetic antioxidant enzymes activity may be a promising way to improve tolerance to salt stress under real-field condition. It is concluded that revealing the molecular nature of chloroplast ion transporters and understanding the modes of their operation will ensure the future sustainability of the world agriculture and the prospects of biological phytoremediation of salinized land via using salt-tolerant crop germplasm.
Apocyni Veneti Folium (AVF) has been raised great interest in the antioxidant properties recently for the preservation of human health. However, little research was found on the integrate metabolites except our previous investigation on the variations of the bioactive constituents. To understand the salt-tolerant mechanisms of the halophyte, metabolomic platform based on ultra-fast liquid chromatography tandem triple time-of-flight mass/mass spectrometer was applied in this study. The results showed that metabolic profiles were separated and differentiated among groups based on multivariate statistical analysis; different metabolites belonged to various chemical classes. Besides, phenylpropanoid pathway and terpenoid biosynthesis were disturbed in all salt-stressed AVF and low salt-treated group appeared to be better than other samples in terms of relative contents (peak areas) of the wide variety of bioactive components and physiological variations of photosynthetic pigments, osmotic homeostasis, lipid peroxidation product and antioxidative enzymes. This study may provide additional insight into the salt-tolerant mechanisms and the quality assessment of AVF in a holistic level based on the plant metabolomics.
Cytokinins are involved in many plant growth and development processes, which also has been shown to function in abiotic stress response. Cytokinin signaling is similar to prokaryotic two-component pathways and includes the transcriptional up-regulation of type-A response regulators (RRs) by cytokinin, which in turn act to inhibit cytokinin responses to provide a negative feedback loop. Cytokinin signaling is composed of several gene families and only a handful full of genes have been studied. Here, we demonstrated the function of two highly identical rice type-A response regulators, OsRR9 and OsRR10, which are both induced by cytokinin and repressed by salinity stress in rice. Loss-of-function osrr9/osrr10 mutants have higher salinity tolerance than wild-type rice seedlings. The transcriptomic analysis uncovered several ion transporters genes which were up-regulated in response to salt in the osrr9/osrr10 mutants relative to the wild-type seedlings. These include high-affinity potassium transporters, such as OsHKT1;1, OsHKT1;3, and OsHKT2;1, which play an important role in sodium and potassium homeostasis. In addition, disruption of OsRR9 and OsRR10 also affects the expression of multiple genes related to photosynthesis, transcription activity, and phytohormone signaling. Together, these results suggest that OsRR9 and OsRR10 function as negative regulators in rice salinity tolerance.
Salt stress affects seed germination and seedling growth. In this study, the effects of solid matrix priming (SMP)and salt stress on broccoli and cauliflower seed germination and early seedling growth were investigated. Physiological and biochemical changes in broccoli and cauliflower seeds and seedlings after the SMP and/or salt stress treatment were determined. Broccoli seeds were primed by mixing the seeds with vermiculite and H 2 O at a ratio of 1:1.5:2 (w/w/v)followed by two days incubation at 15 °C in the dark. Cauliflower seeds were primed by mixing the seeds with vermiculite and H 2 O at a ratio of 1:1.5:1 (w/w/v)followed by two days incubation at 20 °C in the dark. The primed and non-primed seeds were air-dried and then germinated on filter papers pre-wetted with H 2 O containing 0, 50, 100, 150 or 200 mM NaCl. The results showed that, without SMP treatment, the seed germination vigor (GV), germination index (GI)and vitality index (VI)were all inhibited and the mean germination time (MGT)was increased after the treatment with 100, 150 or 200 mM NaCl. The results also showed that the negative effects caused by the salt stress could be alleviated by the SMP treatment. The primed broccoli and cauliflower seeds showed an increase of GV, GI and VI compared with the non-primed seeds under the non-stressed or salt-stressed conditions. In addition, our result showed that the SMP treatment increased the activities of peroxidase and catalase, and the contents of proline, soluble sugar and soluble protein in both broccoli and cauliflower seedlings. We consider that the SMP treatment is useful approach for the improvement of broccoli and cauliflower seed germination and seedling establishment.
The aim of current investigation was to perform proteomics and physio-chemical studies to dissect the changes in contrasting varieties (S-22 and PKM-1) of Lycopersicon esculentum under low-temperature stress. Plant grown under variable low-temperature stress were analysed for their growth biomarkers, antioxidant enzyme activities, and other physiological parameters, which headed toward the determination of protein species responding to low-temperature and 24-epibrassinolide (EBL) concentrations. The plants grown under temperatures, 20/14, 12/7, and 10/3 °C recorded significantly lower growth biomarkers, SPAD chlorophyll, net photosynthetic rate and carbonic anhydrase activity in S-22 and PKM-1. Moreover, the combined effect of EBL and hydrogen peroxide (H 2 O 2 ) significantly improved the parameters mentioned above and consecutively upgraded the different antioxidant enzymes (CAT and SOD) with higher accumulation of proline under stress and stress-free environments. Furthermore, proteomics study revealed that the maximum number of differentially expressed proteins were detected in S-22 (EBL + H 2 O 2 ); while treatment with EBL + H 2 O 2 + low temperature lost expression of 20 proteins. Overall, three proteins (O80577, Q9FJQ8, and Q9SKL2) took a substantial part in the biosynthesis of citrate cycle pathway and enhanced the growth and photosynthetic efficiency of tomato plants under low-temperature stress.
To enhance crop productivity and minimize the harmful effects of various environmental stresses, such as salinity and drought, farmers often use mineral fertilizers. However, inadequate or excessive fertilization can reduce plant growth and nutritive quality and contribute to soil degradation and environmental pollution. This study investigated the effects of salinity (0, 100 or 150 mM NaCl) and nitrogen form (sole NO 3⁻ or NH 4⁺ , or combined NO 3⁻ :NH 4⁺ at 25:75 or 50:50) on growth, photosynthesis, and water and ion status of a commercial variety of maize (Zea mays SY Sincero). In the absence of NaCl, the media containing ammonium only or both nitrogen forms had higher aboveground growth rates than that containing nitrate only. Indeed, the maize growth, expressed as leaf dry matter, seen on NH 4⁺ in the absence of salinity, was nearly double the biomass compared to that with NO 3⁻ treatment. Irrespective of N form, the presence of NaCl severely reduced leaf and roots growth; the presence of ammonium in the nutrient solution diminished these negative effects. Compared to the NH 4⁺ only and combined treatments, the leaves of plants in the NO 3⁻ -only medium showed signs of nitrogen deficiency (general chlorosis), which was more pronounced in the lower than upper leaves, indicating that nitrate is partly replaced by chloride during root uptake. NH 4⁺ favored maize growth more than NO 3⁻ , especially when exposed to saline conditions, and may improve the plant's capacity to osmotically adjust to salinity by accumulating inorganic solutes.
Copper is essential for plant growth, but in excess may cause adverse effects on plant physiology. Harmful effects are also caused by plant exposure to salinity (NaCl) due to the excessive use of fertilizers, soil degradation and/or the quality of the water used for irrigation. The impact of single and combined salinity (Sal) and copper (Cu) stress on spearmint metabolism were studied in hydroponics. Spearmint plants (Mentha spicata L.) were subjected to salinity stress (150 mM NaCl) and/or excessive Cu concentration (60 μM Cu) via the nutrient solution. Not only Sal and Cu, but also their combination suppressed plant growth by decreasing plant biomass, root fresh weight and plant height. Chlorophyll content decreased mainly for the combined stress treatment (Sal+Cu). Polyphenols and antioxidants (FRAP, DPPH, ABTS) increased in single stress treatments (Sal or Cu), but decreased in the combined stress (Sal+Cu). The application of Sal or Cu stress decreased Zn, N and K (leaves), K, Ca, P and Mg (roots) content. Copper application increased Ca and Mg in leaves. In conclusion, salinity stress and Cu exposure may change the primary metabolic pathways in favor of major volatile oil components biosynthesis, resulting in significant changes of essential oil yield and composition.
Soil salinity is one of the major abiotic stress factors that hampers plant growth and productivity by limiting photosynthesis and other related metabolic processes. In this study we investigated whether treatment with proline and/or 24-epibrassinolide (EBL) to two contrasting cultivars of Brassica juncea (L.) Czern and Coss viz. Varuna and RH-30 could counteract with the adverse effects of salinity on photosynthesis and seed yield. Plants were treated with proline and/or 24-epibrassinolide (EBL) at 28 and 29d-stages of growth. Salt stress reduced plant growth, photosynthetic attributes, efficiency of PSII (Fv/Fm), leaf water potential and finally seed yield, at harvest but improved the activity of antioxidant enzymes in both the cultivars in a concentration dependent manner. Exogenous application of EBL with proline completely neutralised the adverse effects of salt at 78 mM or 117 mM stress levels whereas the treatment partially neutralised the impact of highest salt concentration of 156 mM, through the upregulation of the antioxidant system.
Broccoli sprouts produce several bioactive compounds and are recognized as a health-promoting vegetable. In this study, the effect of salinity (NaCl) on the growth of broccoli sprouts was investigated. Broccoli seeds were germinated for 4 and 8 d with spraying 0–120 mM NaCl and then harvested to evaluate changes in endogenous hormones, photosynthetic indices, chlorophyll fluorescence parameters and chloroplast ultrastructure. The growth of sprouts was significantly promoted by low salinity (40 and 80 mM NaCl) and inhibited by high salinity treatment (120, 160 and 200 mM NaCl). In 8-day-old sprouts treated with 80 mM NaCl, levels of abscisic acid, cytokinin, brassinolide, indole-3-acetic acid and gibberellic acid were significantly enhanced, while net photosynthetic rate increased in low salinity conditions was due to the elevated chlorophyll content and increased photosystem II activity. Furthermore, low salinity increased the leaf area maximally in both 4- and 8-day-old sprouts. Enlarged chloroplast and an increased number of grana also contributed to improved photosynthesis. Low salinity conditions induced endogenous growth hormone synthesis and improved photosynthesis, thereby promoting the growth of broccoli sprouts. This study provides a theoretical basis for the improved production of broccoli sprouts in low salinity conditions.
Salinity is among the most detrimental and diffuse environmental stresses. Halophytes are plants that developed the ability to complete their life cycle under high salinity. In this work, a mass spectrometric metabolomic approach was applied to comparatively investigate the secondary metabolism processes involved in tolerance to salinity in three halophytes, namely S. brachiata, S. maritima and S. portulacastrum. Regarding osmolytes, the level of proline was increased with NaCl concentration in S. portulacastrum and roots of S. maritima, whereas glycine betaine and polyols were accumulated in S. maritima and S. brachiata. Important differences between species were also found regarding oxidative stress balance. In S. brachiata, the amount of flavonoids and other phenolic compounds increased in presence of NaCl, whereas these metabolites were down regulated in S. portulacastrum, who accumulated carotenoids. Furthermore, distinct impairment of membrane lipids, hormones, alkaloids and terpenes was observed in our species under salinity. Finally, several other nitrogen containing compounds were involved in response to salinity, including amino acids, serotonin and polyamine conjugates. In conclusion, metabolomics highlighted that the specific mechanism each species adopted to achieve acclimation to salinity differed in the three halophytes considered, although response osmotic stress and oxidative imbalance have been confirmed as the key processes underlying NaCl tolerance.
Salinity is an important environmental factor affecting fish physiology. Tongue sole (Cynoglossus semilaevis) is a euryhaline species that can survive in a wide range of salinity, and might be used as a promising model animal for environmental science. In this study, by using the nuclear magnetic resonance (¹H NMR)-based metabolomics, amino acids analysis and real-time quantitative PCR assay, we investigated the metabolic responses in the gills and plasma of tongue sole subjected to hypo- (0 ppt, S0) and hyper-osmotic stress (50 ppt, S50) from isosmotic environment (30 ppt, S30). The results showed that the metabolic profiles of S50 were significantly different from those of S0 and S30 groups, and a clear overlap was found between the latter two groups. Ten metabolites were significantly different between the salt stress groups and the isosmotic group. Taurine and creatine elevated in both S0 and S50 groups. Choline decreased in S50 group while increased in S0 group. Amino acids and energy compounds were higher in the gills of S50 group. The metabolic network showed that ten metabolic pathways were all found in S50 group, while seven pathways were observed in S0 group. Meanwhile, the transcript levels of the Tau-T and ATP synthase in the gills increased with increasing salinity. Aspartate and methionine exhibited significant differences in the plasma among the groups, but did not show differences in the gills. Comparatively, glutamate exhibited significant differences both in the plasma and the gills. Overall, these findings provide a preliminary profile of osmotic regulation in euryhaline fish.
Indole-3-acetic acid (IAA) and salicylic acid (SA) are two essential phytohormones for plants. Their regulating functions depend on their levels in different locations of plants. However, currently there is no satisfactory method for visual analysis of such small molecules in a whole plant. Herein the levels of IAA and SA in continuous parts of whole pea seedlings were analysed with paper-based electroanalytical devices coupled with a multichannel electrochemical station. The parts of pea seedlings were cut and put on the working electrodes for quantification. The contents of IAA and SA in continuous parts could be presented in the form of heatmaps, illustrating polar distribution of IAA levels and gradual changes of SA levels in whole pea seedlings. The contents distribution of IAA and SA further revealed variation of IAA and SA in different locations of pea seedlings. More importantly, the contents of IAA and SA in pea seedlings under normal conditions and salinity could also be differentiated with heatmaps and the contents distribution. Such results implied that our approach might be able to be extended for the study of mechanisms of plant hormones under various stresses. This study provided a possible route for visualization of small biochemical molecules in vivo with paper-based electrochemical devices.
Thirty crop species provide 90% of our food, most of which display severe yield losses under moderate salinity. Securing and augmenting agricultural yield in times of global warming and population increase is urgent and should, aside from ameliorating saline soils, include attempts to increase crop plant salt tolerance. This short review provides an overview of the processes that limit growth and yield in saline conditions. Yield is reduced if soil salinity surpasses crop‐specific thresholds, with cotton, barley and sugar beet being highly tolerant, while sweet potato, wheat and maize display high sensitivity. Apart from Na⁺, also Cl‐, Mg²⁺, SO42‐ or HCO3‐ contribute to salt toxicity. The inhibition of biochemical or physiological processes cause imbalance in metabolism and cell signalling and enhance the production of reactive oxygen species interfering with cell redox and energy state. Plant development and root patterning is disturbed, and this response depends on redox and reactive oxygen species signalling, calcium and plant hormones. The interlink of the physiological understanding of tolerance processes from molecular processes as well as the agronomical techniques for stabilizing growth and yield and their interlinks might help improving our crops for future demand and will provide improvement for cultivating crops in saline environment.
This article is protected by copyright. All rights reserved.
A field trial consisting of cotton grown employing a combination of ridge planting, mulching with film, and drip irrigation was laid out on a plot with severely saline soil in a typical inland arid area of Xinjiang. The effect of five levels of soil matric potential set up 0.2 m below the drip emitter, namely −5 kPa, −10 kPa, −15 kPa, −20 kPa, and −25 kPa, were studied in terms of changes in soil salinity (ECe), sodicity (SAR), crop growth and yield components. Drip irrigation increased the leaching of soil salts and decreased the ECe and SAR of each soil layer. Although the levels of soil salt rose again, in spring and winter, after irrigation was discontinued, the root zone (0–40 cm) remained less saline: the ECe and SAR value under the soil matric potential of −5 kPa and −10 kPa were 63% and 49% of its values in 2009 respectively, before the land was brought under cultivation (p ≤ 0.05), showing maximum leaching. The yield of cotton peaked at the soil matric potential of −5 kPa. The germination rate, which was the main factor that influenced the cotton yield, was 67% of that in non-saline soil in the first two years, and increased to 84% in the third year. After three years, the rate of germination in all the treatments exceeded 67%, and the highest rate (78%) was at −5 kPa; in the same treatment, boll yield was 4.40 g per plant. Except for germination rate and the yield of lint and seed, all the yield components increased significantly (p ≤0.05) as ECe and SAR decreased in 2010 and 2011. The correlation between soil salt (salinity and sodicity) and other components such as the number of cotton bolls per plant, the average weight of a boll, and lint percentage varied, probably because water supply was being regulated and, as a result, the physicochemical properties of the soil kept changing constantly. Taking into account the extent of leaching, crop growth, and yield, the lower limit for the soil matric potential should be −5 kPa at 20 cm below the dripper for the first three years during reclamation to promote cotton cultivation on the saline-sodic soil of Xinjiang.
Plant growth promoting bacteria (PGPB) endophytes that express 1-aminocyclopropane-1-carboxylate (ACC) deaminase reportedly confer plant tolerance to abiotic stresses such as salinity by lowering stress-related ethylene levels. Two preselected ACC deaminase expressing endophytic Pseudomonas spp. strains, OFT2 and OFT5, were compared in terms of their potential to promote plant growth, leaf water contents, photosynthetic performance, and ionic balance of tomato plants under conditions of moderate NaCl stress (75 mM). Salinity stress strongly affected growth, leaf water contents, and photosynthetic performance of tomato seedlings, and inoculation with either OFT2 or OFT5 ameliorated these adverse effects. Decreases in plant biomass due to salinity stress were significant in both uninoculated control plants and in plants inoculated with OFT2 compared with plants without NaCl stress. However, no reductions in total biomass were observed in plants that were inoculated with the OFT5 strain. Strain OFT5 influenced growth, physiological status, and ionic balance of tomato plants more efficiently than strain OFT2 under NaCl stress. In particular, inoculated OFT5 reduced salt-induced ethylene production by tomato seedlings, and although it did not reduce shoot uptake of Na, it promoted shoot uptake of other macronutrients (P, K, and Mg) and micronutrients (Mn, Fe, Cu, and Zn). These nutrients may activate processes that alleviate the effects of salt, suggesting that OFT5 can be used to improve nutrient uptake and plant growth under moderate salt-affected conditions by reducing stress-related ethylene levels.
Pretreatment in arboriculture is a new physiological approach allowing the improvement of plant tolerance to salt stress. This research aims to screen various pretreatments of salicylic acid (SA) and/or calcium chloride (CaCl2) to mitigate the effect of salinity on ‘Oueslati’ olive plants (Olea europeae L.) on physiological attributes under 200 mmol L⁻¹ of NaCl application. One - year- old plants were transplanted to sand culture in a greenhouse, and were pretreated with two levels of foliar application of SA (0.5 and 1 mmol L⁻¹) and by adding CaCl2 (10 and 20 mmol L⁻¹) to the culture solution twice a week for 45 days. At the end of the pretreatment, the plants were subjected to 200 mmol L⁻¹ NaCl exposure for 75 days. The result showed that shoots and roots growth were decreased significantly due to salinity, sodium (Na⁺) ions increased and K⁺/Na⁺ ratio decreased in leaves. Rate of assimilation (A), transpiration (E) and stomatal conductance (gs) decreased in leaves. Salinity caused significant increase in both malondialdehyde (MDA) and H2O2 concentration, a decrease in total polyphenol and flavonoid levels and an increase in scavenging activity (IC50) (21%). Moreover, salinity caused a decrease in xylem and an increase in phloem thickness in leaves. However, pretreatments could partly improve the adverse effects of salinity on the most studied parameters. SA (1 mmol L⁻¹) is able to restrict Na⁺ ions transport from the roots to the leaves limiting its toxicity in the sensitive organs. SA (1 mmol L⁻¹) and CaCl2 (10 mmol L⁻¹) pretreatment alleviate the effects of salinity on dry weight of shoots and roots as well as, photosynthetic activity in pretreated plants. Moreover, at the same pretreatment, results showed a decrease of the Na⁺ translocation to the leaves. Furthermore, it has been shown that pretreatment of ‘Oueslati’ olive plants enhance the non-enzymatic antioxidant activity (total polyphenol and flavonoid content).These results suggest that pretreatments may be useful methods to increase salt tolerance in olive, for use in arid and semi-arid environments.
Soil salinity adversely affects plant growth, crop yield and the composition of ecosystems. Salinity stress impacts on plants by combined effects of Na⁺ toxicity and osmotic perturbance. Plants have evolved elaborate mechanisms to counteract the detrimental consequences of salinity. Here we reflect on recent advances in our understanding of plant salt tolerance mechanisms. We discuss the embedding of the salt tolerance mediating SOS pathway in plant hormonal and developmental adaptation. Moreover, we review newly accumulating evidence indicating a crucial role of a transpiration dependent salinity tolerance pathway, that is centered around the function of the NADPH oxidase RBOHF and its role in endodermal and Casparian strip differentiation. Together, these data suggest a unifying and coordinating role for Ca²⁺ signaling in combatting salinity stress at the cellular and organismal level.
Salvadora persica L. (Miswak) is a facultative halophyte growing under high saline conditions. It has developed the adaptive characteristics to cope with high salinity because of its extreme habitat. The present study investigates the metabolomic responses of the halophyte S. persica imposed to long term salinity. This study will provide a systematic framework for understanding the underlying mechanisms and metabolic plasticity of S. persica for adaptation under high saline conditions. S. persica seedlings were imposed to various levels of salinity for 60 d. The metabolic profiling was carried out in leaf samples collected from control and NaCl-treated plants using GC-MS and HPLC analysis. The principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA) were used for identifying the variations among control and treated groups. Furthermore, correlation based networking and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were employed for elucidation of metabolic pathways involved in salt tolerance of S. persica. In S. persica, a total of 56 metabolites belonging to different functional classes such as amino acids, TCA cycle intermediates, organic acids, sugars, sugar alcohols, phytohormones and fatty acids were changed by salinity. The fold change analysis showed that salinity induced major metabolic differences were noted for proline, methionine, phenylalanine, phosphonic acid, citric acid, galactaric acid, mandelic acid, caffeic acid, shikimic acid, gulonic acid, D-xylose, D-mannose, D-tagatose, D-manniotol, ABA, jasomonic acid, stearic acid and benzyl amine. Further assessment by correlation-based networking and KEGG pathway enrichment analysis demonstrated that the salinity-induced metabolites are associated with the major biological pathways related to amino acid biosynthesis, energy metabolism, carbohydrate metabolism, glycolysis, gluconeogenesis, pyruvate metabolism, TCA cycle, inositol phosphate metabolism, galactose metabolism and alkaloid biosynthesis. The present study is the first report on metabolomic responses to salinity in the halophyte S. persica. From our study, it was concluded that the coordination between various metabolic processes and pathways in S. persica enable the plant to adapt under extreme saline environment.
GC-MS datasets coupled with multivariate statistical analysis were used to investigate metabolic changes in Kimchi during fermentation and metabolic differences in Kimchi added with various amounts (0, 1.25, 2.5, and 5%) of salts. PCA score plot obtained after 1 day of fermentation were clearly distinguishable by different salinity groups, implying that early fermentation speed varied according to Kimchi salinity. PLS-DA score plot from data obtained on the 50th day of fermentation also showed a clear separation, indicating metabolites of Kimchi were different according to salinity. Concentrations of lactic acid, acetic acid, and xylitol were the highest in Kimchi with 5% salinity while concentration of fumaric acid was the highest in Kimchi with 0% salinity. Rarefaction curves showed that numbers of operational taxonomic units (OTUs) in Kimchi with 5% salinity were higher than those in Kimchi with 0% salinity, implying that Kimchi with 5% salinity had more bacterial diversities. This study highlights the applicability of GC–MS based metabolomics for evaluating fermentative characteristics of Kimchi with different salinities.