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Essential oil composition, physiological and morphological variation in Salvia abrotanoides and S. yangii under drought stress and chitosan treatments
Abstract
Several Salvia species are among the most valuable aromatic herbs used for industrial and pharmaceutical applications. Hence, under greenhouse trial conditions, the effects of chitosan treatment (0, 100, and 200 mg L⁻¹) and water deficiency stress on the morphological, physiological, and biochemical features of two Salvia species were examined. Significant changes were seen in chlorophyll a, root volume, dry and fresh weight, and H2O2 concentration as a result of drought stress. Significant influence of chitosan was found for all studied parameters except root length and malondialdehyde (MDA) content. Hydrogen peroxide (H2O2), proline, and MDA were elevated, while photosynthetic pigments decreased under drought stress. The highest essential oil (EO) content (2.20% d.b.) was recorded under moderate stress condition in the absence of chitosan treatment. Using chitosan topically, it is possible to offset the impact of water scarcity on EO content decline and enhance EO compositions. The compensatory effects of chitosan application under stress conditions were observed on the abundance of EO constituents, such as 1,8-cineol, camphor, bornyl acetate, α-bisabolol, α-cadinol, and α-humulene. Moreover, present results suggested that chitosan application can alleviate the drought damage in studied Salvia species.
... The effect of agronomic practices on the differential responses of pharmacologically useful plant compounds is becoming an important topic nowadays. Some of the recent studies that highlighted the effect of water irrigation levels on different essential oil compounds were presented by [33][34][35]. ...
... First, it calculates the reference evapotranspiration daily from weather data using the Penman-Monteith Equation (ETo) [42]. Then, the crop evapotranspiration (ET) was calculated on daily basis by multiplying the ETo with the crop coefficient (Kc) values of 0.5 from sowing to 3-4 pairs of leaves, 0.9 from 3-4 pairs of leaves to the appearance of male flowers, and 1.1 from the appearance of male flowers to the fruit ripening stage, as also adopted by [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] with hemp plants. The depletion factor of the readily available water was set up as 0.66 [31]. ...
... Hydrodistillation continued for about 2.5 h. EO was dried with anhydrous NA2SO4 and stored in dark glass bottles at 4 °C until analysis [43], as recommended by [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. ...
A field experiment was carried out in Lebanon to assess the agronomic and essential oil characteristics of cannabis as affected by sowing date and irrigation practice. The experiment consisted of a split-plot design with the water regime being the main factor (Iopt-irrigated when the readily available soil water is depleted; I50-receiving 50% of the irrigation amounts in Iopt treatments) and sowing date as the sub-plot factor (mid-April; end of April; mid-May). Biometric and seed quality parameters of the cannabis crop were determined. The essential oils (EO) of the inflorescence were subjected to a multivariate analysis such as principal component analysis (PCA) and hierarchical cluster analysis (HCA). The obtained results revealed that the aboveground fresh biomass, the dry matter, and the plant height were 55.08%, 59.62%, and 43.11% higher in Iopt than in I50, respectively. However, the EO content was neither statistically affected by the irrigation regime nor by the sowing date. Under early sowing, both the water-use efficiency (WUE) for biomass and the EO production reached their highest values. All treatments presented a similar seed composition except that the crude fat and crude protein content were more elevated in Iopt than in I50 treatments. The main extracted essential oils in cannabis inflorescence corresponded to twenty-six identified compounds representing 79.34% of the monoterpenes and 81.25% of the sesquiterpenes. The mon-oterpenes were highly correlated with the irrigation treatment and early-April sowing while the sesquiterpenes were better enhanced under I50 and end of April to mid-May sowing. The study reveals that agronomic practices lead to differential responses of pharmacologically useful plant compounds for improved health benefits. Further research is required to clarify the potential for cannabis cultivation in Lebanon.
... Water shortage stress led to decreased fresh and dry weight of lavender plants, which affected their productivity due to lack of available nutrients caused by drought effects on nitrogen mass flow and phosphorus and potassium release (Soltanbeigi et al., 2021;Kausar et al., 2023). Drought stress reduces lavender yield by causing stomatal closure, inhibiting the Rubisco enzyme, and reducing chlorophyll content and photosynthetic capacity (Khodadadi et al., 2022). AMF + BC treatment improved fresh and dry yield by enhancing plant access to water and nutrients, regulating cell osmotic pressure, and increasing antioxidant activities (Lahbouki et al., 2022;Kausar et al., 2023). ...
... Water stress hinders photosynthesis in plants by reducing the absorption of carbon dioxide through the closing of stomata. As a result, NADPH+H+ levels increase in plant cells, inhibiting photosynthesis (Farouk and Al-Huqail, 2020;Khodadadi et al., 2022). Our findings are in agreement with Ostadi et al. (2020) reported that the percentage of main components and compounds of Mentha x piperita essential oil increased in mild drying. ...
Increasing the productivity of crops in water deficit circumstances is of great significance in order to face the challenge of securing global food production. Nowadays, the use of biochar (BC) and arbuscular mycorrhizal fungi (AMF) are considered as one of the most effective methods for empowering plants to deal with drought stress. However, the literature regarding the effects of the simultaneous use of AMF+BC on plants under drought stress is scarce. Hence, the present study was conducted to consider the combined application of AMF and biochar on the physiological and biochemical properties of lavender under various levels of irrigation. The first factor includes three irrigation regimes of 90% field capacity (FC), 60% FC, and 30% FC, respectively, corresponding to normal irrigation, mild and severe drought stress. The second factor included a fertilizer or microbial inoculant source, which were respectively: no inoculation (control), inoculation with AMF, BC, and co-application of AMF along with BC. The highest nutrient, chlorophyll and carotenoid content, and fresh, and dry weight of lavender were recorded under normal irrigation conditions with combined application of AMF+BC. The combined application of AMF+BC was significantly effective in increasing the activity of antioxidant enzymes against oxidative damage caused by drought stress and in reducing the accumulation of proline and malondialdehyde. An increase in phenolic, flavonoid, and concentration of essential oil was observed under mild stress and using AMF+BC, while the highest essential oil yield was recorded under a normal irrigation regime and treated with AMF+BC. The highest content of linalool, camphor, borneol, and linalyl acetate was obtained in mild stress by adding AMF+BC. It can be concluded that the use of AMF+BC combination treatment may be a useful strategy to improve the quantity and quality of lavender EO in drought-stress circumstances.
... It has been demonstrated that exposing plants to heavy metals leads to severe oxidative stress, primarily due to the generation of high levels of reactive oxygen species (ROS), which can damage essential macromolecules in plant cells [31,91,92]. On the other hand, CS-NPs may boost photosynthesis, leading to an improvement in EO and EOY [93,94]. CS-NP positively impact EO, both under normal and Cr-stress conditions, which may be due to increased enzyme activity and substrate availability [31,95]. ...
An excessive amount of chromium in soil has detrimental effects on plant processes, and impairs food security, and public health. The application of nanoparticles may be a suitable solution and an innovative strategy by which to reduce plant abiotic stresses and pollution in the agricultural ecosystems. This research focuses on the effects of chitosan nanoparticles (CS-NPs) on thyme (Thymus vulgaris L.) plants grown in Cr-contaminated soil. The effects of CS-NPs as a soil amendment at four concentrations were investigated on plant nutrient uptake, photosynthesis parameters, antioxidant system, and essential oil (EO) content under soil Cr stress. The results show that chromium stress reduced fresh and dry weight of shoots, the uptake of macro-, and micro-elements, chlorophyll and carotenoids. The application of CS-NPs improved the antioxidant enzyme activity, reduced malondialdehyde, and increased the content of nutrients, EOs, photosynthetic pigments, and chlorophyll fluorescence parameters. The intermediate dose of chitosan nanoparticles (0.1% w/v) best valorized the content and yield of thyme EOs under chromium stress. These results are indicative that the application of CS-NPs can represent a supportive approach for plant production in soils contaminated with heavy metals.
... This fluctuation may be attributed to the detrimental impact of water stress and drought on essential oil yield, a phenomenon well-supported by existing literature, where water stress have been reported to negatively affects essential oil yield. 43,44 Furthermore, numerous studies have demonstrated that severe water stress can enhance the concentration of essential oils, with the highest yield occurring under conditions of moderate water stress, [45][46][47][48][49][50] further reinforcing the findings from the present study. ...
Climate change poses a threat to plant and animal biodiversity. It induces physiological and
morphological changes in plants. This study aimed to assess the effect of climate change on the
phytochemical constituents, essential oil yield and chemical composition of Inula viscosa leaves.
Three samples of I. viscosa from the Taounate region of Morocco were cultivated in a closed
chamber for three years under different climatic conditions: sample 1 (I. viscosa cultivated in the
first year under normal temperature and precipitation conditions of Taounate region), sample 2 (I.
viscosa cultivated in the second year, at 5°C increase in temperature and 50% decrease in
precipitation), and sample 3 (I. viscosa cultivated in the third year, at 10°C increase in temperature
and 75% decrease in precipitation). Phytochemical and mineral analyses of the three samples were
done according to standard procedures. Essential oils were extracted from the leaves of the three
samples by hydro-distillation using the Clavenger apparatus. Chemical composition of the
essential oils was identified by gas chromatography-mass spectrometric (GC-MS) analysis.
Phytochemical screening showed that moderately intensified climatic conditions (sample 2) led to
an increase in phytochemical content, mineral composition, and essential oil yield of Inula viscosa
leaves. However, at adverse climatic conditions (sample 3), the phytochemical content, mineral
composition, and essential oil yield of Inula viscosa leaves decreased significantly. GC-MS
analysis revealed that changes in climatic condition affected the content of major compounds in
the essential oil of I. viscosa leaves. Therefore, climate change can significantly impact the
chemical composition of plants.
... The presence of N, P and micronutrients was correlated with increased VOs production in several plants [40 and 41]. The efficiency of CH in the raise of plant growth and secondary metabolites biosynthesis in numerous aromatic species has been reviewed [42] for example [32] on lemongrass, [43] on sweet basil, and [44] on salvia plants. They suggested that an elicitor such as CH can efficiently induce different phytochemicals including VOs. ...
... stress via improving Chl content has been reported on Salvia abrotanoides (Khodadadi et al. 2022) and Catharanthus roseus (Ali et al. 2021), which is in line with the current findings. Furthermore, AsA can minimize the negative effects of drought stress on plants by dealing with dangerous oxidants that have been documented to damage plant membranes such as the thylakoid membrane of chloroplasts (Khazaei and Estaji 2020). ...
Although the positive role of chitosan and ascorbic acid (AsA) in modulating drought stress has been discovered in plants, there is no available data on their co-application on medicinal plants under water limitation. The present study aimed to discover the effect of chitosan and AsA on plant growth and physio-biochemical attributes of common chicory (Cichorium intybus L.) at different irrigation regimes. A split plot factorial experiment was carried out with the main plot of irrigation regimes at 60 mm, 90 mm, and 120 mm evaporation from Class A pan as normal irrigation, moderate, and severe drought, respectively, and foliar application of chitosan (50 mM and 100 mM) and AsA (4 mM) in the subplots during 2020 and 2021. The results showed that without chitosan and AsA, severe drought stress led to decreased shoot yield (59%), root yield (32%), chlorophyll (Chl, 30%), relative water content (RWC, 20%), saturated fatty acid (SFAs, 23%), and monounsaturated fatty acids (MUFAs, 12%) but increased electrolyte leakage (EL, 23%) and polyunsaturated fatty acids (PUFAs, 10%) compared with normal irrigation. However, the interactions of chitosan and AsA with an adjusting role in drought improved the growth and biochemical attributes. Total phenolic content (TPC) in plants exposed to moderate drought and sprayed with chitosan at 50 mM or AsA was higher than other treatments. The heat map showed that TPC and shoot yield represented the high variability during the experiment, which can be determined as indicators for discovering the physiological and biochemical changes in common chicory. The present work suggested the co-application of chitosan at 50–100 mM and AsA at 4 mM can alleviate drought stress on common chicory in arid and semiarid areas.
... The mixture of common chili (Capsicum annuum) fruit extracts and chitosan can be effective against pathogenic bacteria, especially against Staphylococcus aureus, which is a Gram-positive, spherically shaped bacterium [104]. A chitosan application increased the content of the EO components, the positive impacts of chitosan utilization under drought stress conditions [105]. The usage of water-soluble carboxymethyl chitosan-grafted daphnetin nanoparticles (DA@CMCS-NPs) improved the activities of defense enzymes in tobacco, and effectively inhibited the development of tobacco bacterial wilt (Ralstonia solanacearum) [106]. ...
Chitosan is illustrated in research as a stimulant of plant tolerance and resistance that promotes natural defense mechanisms against biotic and abiotic stressors, and its use may lessen the amount of agrochemicals utilized in agriculture. Recent literature reports indicate the high efficacy of soil or foliar usage of chitin and chitosan in the promotion of plant growth and the induction of secondary metabolites biosynthesis in various species, such as Artemisia annua, Curcuma longa, Dracocephalum kotschyi, Catharanthus roseus, Fragaria × ananassa, Ginkgo biloba, Iberis amara, Isatis tinctoria, Melissa officinalis, Mentha piperita, Ocimum basilicum, Origanum vulgare ssp. Hirtum, Psammosilene tunicoides, Salvia officinalis, Satureja isophylla, Stevia rebaudiana, and Sylibum marianum, among others. This work focuses on the outstanding scientific contributions to the field of the production and quality of aromatic and medicinal plants, based on the different functions of chitosan and chitin in sustainable crop production. The application of chitosan can lead to increased medicinal plant production and protects plants against harmful microorganisms. The effectiveness of chitin and chitosan is also due to the low concentration required, low cost, and environmental safety. On the basis of showing such considerable characteristics, there is increasing attention on the application of chitin and chitosan biopolymers in horticulture and agriculture productions.
... Biostimulants have several applications in agriculture and the main categories are amino acids, chitosan, humic and fulvic acids, seaweed extracts, nitrogen-fixing bacteria (e.g., Azotobacter spp., Rhizobium spp.), and phosphorus solubilizing micro-organisms (e.g., Bacillus subtilis) [22][23][24][25][26][27]. Chitosan is a polysaccharide that promotes the growth of plants [28], improves the crop productivity [29], alleviates the negative effects of abiotic stress on plant growth [30,31], and induces defense mechanisms against pathogens such as Sclerotinia sclerotiorum and the cucumber mosaic virus [32,33]. Based on the above, it is of great importance to study the effect of chitosan on the growth and productivity of underutilized leafy greens with high nutritional value. ...
Bristly oxtongue (Helminthotheca echioides (L.) Holub) is a broad-leaved weed species that is commonly found in cereal crops. However, it is also an edible species whose leaves are consumed at the rosette growth stage of the plant. Three pot experiments were conducted to evaluate different cultivation protocol suggestions for this underutilized wild leafy vegetable. In the first experiment, early sowing (14 October) increased the rosette diameter and fresh biomass of bristly oxtongue compared with late sowing (13 November). In the second experiment, the application of calcium ammonium nitrate (26-0-0) at a rate of 100 kg ha−1 (N10 treatment) increased the relative chlorophyll content in the leaves compared with the control treatment. Similarly, the highest rosette diameter, leaf number, and fresh biomass values were recorded in the N10 treatment, while chitosan application had no impact on growth of plants. In the third experiment, increased root dry biomass was obtained with top dressing application of calcium ammonium nitrate at a rate of 100 kg N ha−1 compared with 0 or 50 kg N ha−1, regardless of the basal fertilization (15-5-20) rate applied. Moreover, the highest rosette diameter, relative chlorophyll content, and fresh biomass values were recorded in the treatment where the highest top dressing rate of calcium ammonium nitrate was applied. In conclusion, our results reveal that the appropriate selection of the sowing date, as well as the combination of the basal fertilizer (15-5-20) at a rate of 250 kg ha−1 with 100 kg N ha−1 calcium ammonium nitrate, can maximize the growth and yield of bristly oxtongue.
Salvia subg. Perovskia is an aromatic medicinal plant from the Lamiaceae family. Essential oil (EO) content and composition, along with enzymatic and non-enzymatic antioxidants, were evaluated in 18 plant populations under three levels of irrigation for two consecutive years. Based on the GC-MS analysis, the main components of EO were borneol (1.18-36.53%), followed by camphor (0.54-32.17%), 1,8-cineole (12.44-29.26%), δ-3-carene (0.39-21.20%), myrcene (0.59-16.28%), and α-pinene (0.79-12.87%) in the studied treatment. Except for malondialdehyde and hydrogen peroxide in leaves and roots, all the examined parameters showed lower values in the first harvest year compared to those of the second year. The activities of antioxidant enzymes, total phenolics, and flavonoids of the extracts were substantially enhanced as stress intensified to reach maximum values in leaves under severe stress and in roots under moderate stress conditions. The maximum root tan-shinones content was observed under moderate water deficit conditions, while the highest EO content was obtained in plants exposed to severe stress conditions. Taking into account the evidence provided by this study, it can be inferred that the use of water deficit stress can serve as an effective method to stimulate and improve antioxidant properties, as well as the quantity and quality of secondary metabolites in Salvia subg. Perovskia.
In this research, a HPLC analysis, along with transcriptomics tools, was applied to evaluate chitosan and water stress for the prediction of phenolic flavonoids patterns and terpenoid components accumulation in Salvia abrotanoides Karel and S. yangii. The results indicated that the tanshinone contents under drought stress conditions increased 4.2-fold with increasing drought stress intensity in both species. The rosmarinic acid content in the leaves varied from 0.038 to 11.43 mg/g DW. In addition, the flavonoid content was increased (1.8 and 1.4-fold) under mild water deficit conditions with a moderate concentration of chitosan (100 mg L−1). The application of foliar chitosan at 100 and 200 mg L−1 under well-watered and mild stress conditions led to increases in hydroxyl cryptotanshinone (OH-CT) and cryptotanshinone (CT) contents as the major terpenoid components in both species. The expressions of the studied genes (DXS2, HMGR, KSL, 4CL, and TAT) were also noticeably induced by water deficit and variably modulated by the treatment with chitosan. According to our findings, both the drought stress and the application of foliar chitosan altered the expression levels of certain genes. Specifically, we observed changes in the expression levels of DXS and HMGR, which are upstream genes in the MEP and MVA pathways, respectively. Additionally, the expression level of KSL, a downstream gene involved in diterpenoid synthesis, was also affected. Finally, the present investigation confirmed that chitosan treatments and water stress were affected in both the methylerythritol phosphate pathway (MEP) and mevalonate (MVA) pathways, but their commitment to the production of other isoprenoids has to be considered and discussed.
Lavandula latifolia Medik. is an aromatic-medicinal plant, native to the Mediterranean region, for which economic interest is mainly focused on the production of essential oil. In the Mediterranean area, the negative effects of climate change, with increasingly frequent extreme heatwaves and drought episodes, have led to the need to select plants with greater tolerance of such scenarios for the future development of this rainfed crop. In the current study, young plants of spike lavender were subjected to a first episode of water deprivation. Subsequently, clones from the surviving ecotypes (SL1 to SL8) were assigned randomly to two homogeneous groups. One group was irrigated to field capacity (as a control) and the other was subjected to water stress for two months. In the leaves of control and stressed plants, physiological parameters including relative water content (%RWC), hydric potential (ΨWP), proline, and abscisic acid were measured. The plant antioxidant defense system was also explored, through analysis of non-enzymatic antioxidants (α-tocopherol, plastochromanol-8), lipid peroxidation (MDA), and photosynthetic pigments (chlorophylls a and b, and carotenoids). The polyphenolic profile was determined and its corresponding antioxidant activity was analyzed for the first time in the early growth stages of this species. Under the drought treatment, the values of the physiological parameters were similar in all ecotypes and changed as the dehydration advanced. However, the response of the antioxidant defense to drought was variable depending on the ecotype under study. As a general pattern, there was a reduction in the concentration of photosynthetic pigments. Although, no statistical differences were detected in α-tocopherol and PC-8, in most cases, the MDA values increased significantly after the drought episode. In the polyphenolic profile identified, p-coumaric acid glycoside and rosmarinic acid-3–O-glucoside were the major components quantified, salvianic acid and O-coumaric acid being described for the first time in this species. Regarding the response of these chemical components to water stress, the concentrations of most polyphenols decreased, with the exception of rosmarinic acid, whose concentration after the stress was higher in three of the eight ecotypes under study. This increment was reflected in a higher in vitro antioxidant capacity. These findings suggest that L. latifolia was affected by drought, even though it showed some strategies to counteract the negative effects of dehydration. The intraspecific variation in the response to dehydration can be considered a useful tool for the preselection of ecotypes with greater resistance to this stress.
Kuraklık stresinin fesleğenin (Ocimum basilicum L.) mikro-morfolojik ve fizyolojik parametrelerine etkisini değerlendirmek amacıyla bitkiler kontrollü ortam koşullarında 3 ay boyunca yetiştirilmiştir. Kuraklık uygulamaları 5 günde bir sulama (kontrol grubu), 10 günde bir sulama (1. grup: düşük derecede stres), 15 günde bir sulama (2. grup: orta derecede stres) ve 20 günde bir 100 ml sulama (3. grup: şiddetli stres) yapılmıştır. Stresin en belirgin etkisi olarak orta seviyedeki kuraklık uygulamasında stoma sayısının arttığı ve stomaların küçüldüğü belirlendi. Stresin şiddeti arttıkça bu parametrelerde herhangi bir değişim olmadı. Benzer etki yaprağın her iki yüzeyinde bulunan capitat ve peltat glandular tüylerde de tespit edildi. Kuraklık stresi fitokimyasal içeriğini de etkiledi. Kuraklık stresi uygulamaları arasında önemli farklılıklar gözlenmemesine rağmen, kuraklık uygulamaları ile kontrol grubu arasındaki farklılık önemliydi. Sonuç olarak, uygulamalar arasındaki farklılıklar ile oluşan mikro-morfolojik ve fizyolojik değişimler fesleğen bitkisinin sekonder metabolit üretimini maksimum tutacak sulama düzeyi olarak belirlenmesini sağlamıştır.
Traumatic brain injury (TBI) signifies a major cause of death and disability. TBI causes central nervous system (CNS) damage under a variety of mechanisms, including protein aggregation, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Astrocytes and microglia, cells of the CNS, are considered the key players in initiating an inflammatory response after injury. Several evidence suggests that activation of astrocytes/microglia and ROS/LPO have the potential to cause more harmful effects in the pathological processes following traumatic brain injury (TBI). Previous studies have established that lupeol provides neuroprotection through modulation of inflammation, oxidative stress, and apoptosis in Aβ and LPS model and neurodegenerative disease. However, the effects of lupeol on apoptosis caused by inflammation and oxidative stress in TBI have not yet been investigated. Therefore, we explored the role of Lupeol on antiapoptosis, anti-inflammatory, and antioxidative stress and its potential mechanism following TBI. In these experiments, adult male mice were randomly divided into four groups: control, TBI, TBI+ Lupeol, and Sham group. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of lupeol against neuroinflammation, oxidative stress, and apoptosis. Lupeol treatment reversed TBI-induced behavioral and memory disturbances. Lupeol attenuated TBI-induced generation of reactive oxygen species/lipid per oxidation (ROS/LPO) and improved the antioxidant protein level, such as nuclear factor erythroid 2-related factor 2 (Nrf2) and heme-oxygenase 1 (HO-1) in the mouse brain. Similarly, our results indicated that lupeol treatment inhibited glial cell activation, p-NF-κB, and downstream signaling molecules, such as TNF-α, COX-2, and IL-1β, in the mouse cortex and hippocampus. Moreover, lupeol treatment also inhibited mitochondrial apoptotic signaling molecules, such as caspase-3, Bax, cytochrome-C, and reversed deregulated Bcl2 in TBI-treated mice. Overall, our study demonstrated that lupeol inhibits the activation of astrocytes/microglia and ROS/LPO that lead to oxidative stress, neuroinflammation, and apoptosis followed by TBI.
Abstract: Drought stress, being the inevitable factor that exists in various environments without recognizing borders and no clear warning thereby hampering plant biomass production, quality,
and energy. It is the key important environmental stress that occurs due to temperature dynamics, light intensity, and low rainfall. Despite this, its cumulative, not obvious impact and multidimensional nature severely affects the plant morphological, physiological, biochemical and molecular attributes with adverse impact on photosynthetic capacity. Coping with water scarcity, plants evolve various complex resistance and adaptation mechanisms including physiological and biochemical responses, which differ with species level. The sophisticated adaptation mechanisms and regularity network that improves the water stress tolerance and adaptation in plants are briefly discussed. Growth pattern and structural dynamics, reduction in transpiration loss through altering stomatal conductance and distribution, leaf rolling, root to shoot ratio dynamics, root length
increment, accumulation of compatible solutes, enhancement in transpiration efficiency, osmotic and hormonal regulation, and delayed senescence are the strategies that are adopted by plants under water deficit. Approaches for drought stress alleviations are breeding strategies, molecular and genomics perspectives with special emphasis on the omics technology alteration i.e., metabolomics,
proteomics, genomics, transcriptomics, glyomics and phenomics that improve the stress tolerance in plants. For drought stress induction, seed priming, growth hormones, osmoprotectants, silicon (Si), selenium (Se) and potassium application are worth using under drought stress conditions in plants. In addition, drought adaptation through microbes, hydrogel, nanoparticles applications and metabolic engineering techniques that regulate the antioxidant enzymes activity
for adaptation to drought stress in plants, enhancing plant tolerance through maintenance in cell homeostasis and ameliorates the adverse effects of water stress are of great potential in agriculture.
Drought stress, being the inevitable factor that exists in various environments without recognizing borders and no clear warning thereby hampering plant biomass production, quality, and energy. It is the key important environmental stress that occurs due to temperature dynamics, light intensity, and low rainfall. Despite this, its cumulative, not obvious impact and multidimen-sional nature severely affects the plant morphological, physiological, biochemical and molecular attributes with adverse impact on photosynthetic capacity. Coping with water scarcity, plants evolve various complex resistance and adaptation mechanisms including physiological and biochemical responses, which differ with species level. The sophisticated adaptation mechanisms and regularity network that improves the water stress tolerance and adaptation in plants are briefly discussed. Growth pattern and structural dynamics, reduction in transpiration loss through altering stomatal conductance and distribution, leaf rolling, root to shoot ratio dynamics, root length increment, accumulation of compatible solutes, enhancement in transpiration efficiency, osmotic and hormonal regulation, and delayed senescence are the strategies that are adopted by plants under water deficit. Approaches for drought stress alleviations are breeding strategies, molecular and genomics perspectives with special emphasis on the omics technology alteration i.e., metabo-lomics, proteomics, genomics, transcriptomics, glyomics and phenomics that improve the stress tolerance in plants. For drought stress induction, seed priming, growth hormones, osmoprotect-ants, silicon (Si), selenium (Se) and potassium application are worth using under drought stress conditions in plants. In addition, drought adaptation through microbes, hydrogel, nanoparticles applications and metabolic engineering techniques that regulate the antioxidant enzymes activity for adaptation to drought stress in plants, enhancing plant tolerance through maintenance in cell homeostasis and ameliorates the adverse effects of water stress are of great potential in agriculture.
The cultivated potato (Solanum tuberosum L.) is currently the third most important food crop in the world and is becoming increasingly important to the local economies of developing countries. Climate change threatens to drastically reduce potato yields in areas of the world where the growing season is predicted to become hotter and drier. Modern potato is well known as an extremely drought susceptible crop, which has primarily been attributed to its shallow root system. This review addresses this decades old consensus, and highlights other, less well understood, morphophysiological features of potato which likely contribute to drought susceptibility. This review explores the effects of drought on these traits and goes on to discuss phenotypes which may be associated with drought tolerance in potato. Small canopies which increase harvest index and decrease evapotranspiration, open stem-type canopies which increase light penetration, and shallow but densely rooted cultivars, which increase water uptake, have all been associated with drought tolerance in the past, but have largely been ignored. While individual studies on a limited number of cultivars may have examined these phenotypes, they are typically overlooked due to the consensus that root depth is the only significant cause of drought susceptibility in potato. We review this work, particularly with respect to potato morphology, in the context of a changing climate, and highlight the gaps in our understanding of drought tolerance in potato that such work implies.
Subgenus Perovskia of the extended genus of Salvia comprises several Central Asian medicinal and aromatic species, of which S. yangii and S. abrotanoides are the most widespread. These plants are cultivated in Europe as robust ornamentals, and several cultivars are available. However, their medicinal potential remains underutilized because of limited information about their phytochemical and genetic diversity. Thus, we combined an ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS) based metabolomics with DNA barcoding approach based on trnH-psbA and ITS2 barcodes to clarify the relationships between these two taxa. Metabolomic analysis demonstrated that aerial parts are more similar than roots and none of the major compounds stand out as distinct. Sugiol in S. yangii leaves and carnosic acid quinone in S. abrotanoides were mostly responsible for their chemical differentiation, whereas in roots the distinction was supported by the presence of five norditerpenoids in S. yangii and two flavonoids and one norditerpenoid in S. abrotanoides. To verify the metabolomics-based differentiation, we performed DNA authentication that revealed S. yangii and S. abrotanoides to be very closely related but separate species. We demonstrated that DNA barcoding coupled with parallel LC-MS profiling constitutes a powerful tool in identification of taxonomically close Salvia species.
Drought is a critical environmental constraint limiting plant growth and productivity. Chitosan has been utilized as a potential biostimulant and proven to be effective against drought stress in many plant species. The objective of this study was to determine the effects of pretreatment with different molecular weight (MW) chitosans on some physiological characteristics of rice seedlings under drought stress. Rice seedlings were treated with low (50-190 kDa), medium (190-310 kDa) and high (310-375 kDa) MW chitosans by seed priming and foliar spray. The seedlings were subjected to drought by withholding water for four days. The relative water content (RWC) was reduced from 93% in the control plants to 74% in the droughted plants. The results revealed that treating with chitosan, especially with low MW chitosan, promoted root growth under drought stress. All chitosan treatments led to higher relative water content and photosynthetic pigment under drought condition. Pretreatment with chitosan also induced sugar accumulation, and treating with low MW chitosan significantly increased starch accumulation under drought stress. In addition, chitosan treatments alleviated the effects caused by drought stress as represented by the decreases in electrolyte leakage, malondialdehyde (MDA) as well as hydrogen peroxide (H2O2), corresponding with the increases in activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) activity.
Chitosan, a copolymer of N-acetyl-D-glucosamine and D-glucosamine, which possesses properties that make it useful in various fields, is produced by the deacetylation of chitin derivatives. It is used in agriculture as a biostimulant for plant growth and protection, it also induces several responsive genes, proteins, and secondary metabolites in plants. Chitosan elicits a signal transduction pathway and transduces secondary molecules such as hydrogen peroxide and nitric oxide. Under biotic stress, chitosan can stimulate phytoalexins, pathogenesis-related proteins, and proteinase inhibitors. Pretreatment of chitosan before exposure to abiotic stresses (drought, salt, and heat) induces plant growth, production of antioxidant enzymes, secondary metabolites, and abscisic acid (ABA). It also causes changes in physiology, biochemistry, and molecular biology of the plant cells. However, plant responses depend on different chitosan-based structures, concentrations, species, and developmental stages. This review collects updated information on chitosan applications, particularly in plant defense responses to biotic and abiotic stress conditions.
Origanum is one of the most important medicinal plants used worldwide due to the economic importance, quantity and quality of essential oil and antioxidant properties. Drought is one of the major abiotic stresses that cause deleterious damage to plants. As a bio-elicitor, chitosan prevents severe damage to plants under stress conditions by triggering plant defense mechanisms. To investigate the effects of chitosan application and water deficit stress on growth, yield and secondary metabolites of origanum, a greenhouse study was performed in a factorial experiment based on randomized complete block design (RCBD) with three replications. The studied factors consisted of foliar application of chitosan at three levels (0, 250 and 500 mg/L), under well-watered and water deficit stress conditions in two origanum species (Origanum majorana and Origanum vulgare). The application of water deficit stress and foliar treatment with chitosan (three steps) was performed three weeks before flowering. Results showed that the water deficit stress reduced the plant dry weight, while increased total phenol and essential oil contents. However, foliar application of chitosan at 500 mg/L under water deficit stress conditions increased dry weight of shoots, and phenol content. Application of chitosan at 250 mg/L increased the content of essential oil compared to the control. Results also showed that application of chitosan as a bio-elicitor can reduce the adverse effects of water deficit stress on marjoram plant. The analysis of GC/MS apparatus revealed that 33 compounds were identified in essential oil, in which γ‑terpinene, cis-sabinene hydrate and terpinolene were the dominant in the oil of both origanum species.
Soybean (Glycine max), as an important oilseed crop, is constantly threatened by abiotic stress, including that caused by salinity and drought. bZIP transcription factors (TFs) are one of the largest TF families and have been shown to be associated with various environmental-stress tolerances among species; however, their function in abiotic-stress response in soybean remains poorly understood. Here, we characterized the roles of soybean transcription factor GmbZIP15 in response to abiotic stresses. The transcript level of GmbZIP15 was suppressed under salt-and drought-stress conditions. Overexpression of GmbZIP15 in soybean resulted in hypersensitivity to abiotic stress compared with wild-type (WT) plants, which was associated with lower transcript levels of stress-responsive genes involved in both abscisic acid (ABA)-dependent and ABA-independent pathways, defective stomatal aperture regulation, and reduced antioxidant enzyme activities. Furthermore, plants expressing a functional repressor form of GmbZIP15 exhibited drought-stress resistance similar to WT. RNA-seq and qRT-PCR analyses revealed that GmbZIP15 positively regulates GmSAHH1 expression and negatively regulates GmWRKY12 and GmABF1 expression in response to abiotic stress. Overall, these data indicate that GmbZIP15 functions as a negative regulator in response to salt and drought stresses.
Background
Chitosan (CTS), a natural polysaccharide, exhibits multiple functions of stress adaptation regulation in plants. However, effects and mechanism of CTS on alleviating salt stress damage are still not fully understood. Objectives of this study were to investigate the function of CTS on improving salt tolerance associated with metabolic balance, polyamine (PAs) accumulation, and Na⁺ transport in creeping bentgrass (Agrostis stolonifera).
Results
CTS pretreatment significantly alleviated declines in relative water content, photosynthesis, photochemical efficiency, and water use efficiency in leaves under salt stress. Exogenous CTS increased endogenous PAs accumulation, antioxidant enzyme (SOD, POD, and CAT) activities, and sucrose accumulation and metabolism through the activation of sucrose synthase and pyruvate kinase activities, and inhibition of invertase activity. The CTS also improved total amino acids, glutamic acid, and γ-aminobutyric acid (GABA) accumulation. In addition, CTS-pretreated plants exhibited significantly higher Na⁺ content in roots and lower Na⁺ accumulation in leaves then untreated plants in response to salt stress. However, CTS had no significant effects on K⁺/Na⁺ ratio. Importantly, CTS enhanced salt overly sensitive (SOS) pathways and also up-regulated the expression of AsHKT1 and genes (AsNHX4, AsNHX5, and AsNHX6) encoding Na⁺/H⁺ exchangers under salt stress.
Conclusions
The application of CTS increased antioxidant enzyme activities, thereby reducing oxidative damage to roots and leaves. CTS-induced increases in sucrose and GABA accumulation and metabolism played important roles in osmotic adjustment and energy metabolism during salt stress. The CTS also enhanced SOS pathway associated with Na⁺ excretion from cytosol into rhizosphere, increased AsHKT1 expression inhibiting Na⁺ transport to the photosynthetic tissues, and also up-regulated the expression of AsNHX4, AsNHX5, and AsNHX6 promoting the capacity of Na⁺ compartmentalization in roots and leaves under salt stress. In addition, CTS-induced PAs accumulation could be an important regulatory mechanism contributing to enhanced salt tolerance. These findings reveal new functions of CTS on regulating Na⁺ transport, enhancing sugars and amino acids metabolism for osmotic adjustment and energy supply, and increasing PAs accumulation when creeping bentgrass responds to salt stress.
Populus euphratica Oliv., the Euphrates poplar, is the tallest tree species in the arid desert areas of Northwest China. Investigation of its drought-resistance genes is valuable to increase understanding of drought resistance mechanisms. RNA-seq of leaves and roots under drought simulation by 25% polyethylene glycol-6000 (PEG 6000) were performed at 0, 4, and 12 h. Leaves and roots responded differently to drought via differentially upregulated and downregulated genes; more genes were downregulated than upregulated in both leaves and roots. Additionally, these differentially expressed genes were enriched in different GO terms and KEGG pathways. For example, GO term ‘response to organic substance’ and KEGG pathway ‘nitrogen metabolism’ were enriched for drought-stressed leaves, while GO term ‘cell wall organization or biogenesis’ and KEGG pathway ‘zeatin biosynthesis’ were enriched for drought-stressed roots. The enrichment of the GO term ‘enzyme linked receptor protein signalling pathway’ in both leaf and root drought responses suggests that these tissues may also have similar mechanisms. However, roots under drought stress for four hs responded by activating programed cell death. The KEGG pathway ‘plant hormone signal transduction’ was detected for 4- and 12-h drought-stressed leaves and 12-h drought-stressed roots, suggesting that plant hormone signal transduction plays an important role in both roots and leaves. GO enrichment of upregulated and downregulated genes for leaves and roots reflect differentially regulatory mechanisms of response to drought stress via different biological processes such as the regulation of photosynthesis and auxin signalling pathway in leaves, and the regulation of defence response and water homeostasis in roots. Fifteen candidate genes, including transcription factors, protein kinase, transporter, late embryogenesis abundant protein and mannitol dehydrogenase, were further selected to determine their response to drought using qRT-PCR. The results show that the expression patterns of 13 of the 15 genes correspond to the RNA-seq results. This study provides new insights into the drought response mechanism of P. euphratica and suggests new candidate gene resources.
Chitosan is a natural biopolymer modified from chitins which act as a potential biostimulant and elicitor in agriculture. It is non-toxic, biodegradable and biocompatible which favors potentially broad application. It enhances the physiological response and mitigates the adverse effect of abiotic stresses through stress transduction pathway via secondary messenger(s). Chitosan treatment stimulates photosynthetic rate, stomatal closure through ABA synthesis; enhances antioxidant enzymes via nitric oxide and hydrogen peroxide signaling pathways, and induces production of organic acids, sugars, amino acids and other metabolites which are required for the osmotic adjustment, stress signaling, and energy metabolism under stresses. It is also known to form complexes with heavy metals and used as tool for phytoremediation and bioremediation of soil. Besides, this is used as antitranspirant compound through foliar application in many plants thus reducing water use and ensures protection from other negative effects. Based on such beneficial properties, chitosan is utilized in sustainable agricultural practices owing to changing climates. Our review gathers the recent information on chitosan centered upon the abiotic stress responses which could be useful in future crop improvement programs.
Essential oil (EO) composition, phenolic content, and antioxidant activity were investigated in 17 P. abrotanoides populations collected from different geographical regions in Iran. The highest (3.61%) and lowest (1.25%) essential oil yields were measured in populations from Semnan Province (PSESM2) and PISKS from Isfahan Province, respectively. GC‐MS analysis identified camphor (4.05‐35.94%), 1,8‐cineole (7.15‐24.34%), borneol (0‐21.75%), and α‐pinene (2.05‐10.33%) as the main constituents of Perovskia essential oil. Cluster analysis classified the studied populations into four different groups: I) high camphene, II) high camphor/1,8‐cineole, III) high borneol/δ‐3‐carene, and IV) high α‐cadinol/trans‐caryophyllene. The highest flavonoid and phenolic contents were detected in PISAK from Isfahan Province (4.09 ± 0.05 mgQE/gDW, 58.51 ± 1.63 mgGAE/gDW) and PKRGS from Khorasan Province (3.80 ± 0.002 mgQE/gDW, 66.86 ± 0.002 mgGAE/gDW). DPPH and reducing power activity model systems identified PMASA and PKRKL as the populations with the highest antioxidant activity. Finally, the data obtained represented valuable information for introducing elite populations with EO components favorable to pharmaceutical and industrial applications.
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A research trial was planned to find out the effect of water deficit and/or silicon (Si) foliar application on the growth, yield, sepal quality and some physiological characters of roselle plants. Under water stress treatment, the growth parameters (plant height, branch number, dry weight and leaf area) sepal yield and relative water content (RWC) were significantly reduced; however Si treatment ameliorated the negative effects of water stress and improved the growth even with non-stressed plants. The contents of N, P, K, Ca and Mg were significantly decreased in water stressed plants relative to plants grown under higher water levels. Si application increased the contents of N, P, K and Mg, while Ca content was decreased due to Si treatment in stressed or non-stressed plants. Water stress significantly decreased the total soluble solids and pH value however; Si application substantially alleviated this reduction. In contrast, the anthocyanin content was significantly increased due to water stress treatment. Otherwise, Si application increased anthocyanin content in stressed or non-stressed plants. Water stress significantly decreased the chlorophyll content and membrane stability index (MSI) compared with non-stressed plants. However, Si application had positive effects in this respect and alleviated the adverse effects of water stress. The total soluble sugars and proline content were significantly increased under water stress conditions and/or Si application. Water stress treatment promoted the activities of CAT, SOD and POD enzymes in roselle leaves however; Si application increased the activities of those enzymes except POD that decreased.
The metabolic cross-talk between the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways was analyzed in spike lavender (Lavandula latifolia Med) on the basis of 13CO2-labelling experiments using wildtype and transgenic plants overexpressing the 3-hydroxy-3-methylglutaryl CoA reductase (HMGR), the first and key enzyme of the MVA pathway. The plants were labelled in the presence of 13CO2 in a gas chamber for controlled pulse and chase periods of time. GC/MS and NMR analysis of 1,8-cineole and camphor, the major monoterpenes present in their essential oil, indicated that the C5-precursors, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) of both monoterpenes are predominantly biosynthesized via the MEP pathway. Surprisingly, overexpression of HMGR did not have significant impact upon the crosstalk between the MVA and MEP pathways indicating that the MEP route is the preferred pathway for the synthesis of C5 monoterpene precursors in spike lavender.
Thymus daenensis, a perennial herb, is often grown in areas that experience drought conditions during its growing period. Application of chitosan may compensate for the negative impact of drought stress on the yield of oil and secondary metabolites in Thymus. The interactive effects of foliar application of chitosan and drought stress on dry matter, essential oil yield, and selected physiological characteristics including photosynthetic pigments, osmotic adjustment, and lipid peroxidation of Thymus were investigated in a two-year study from 2014 to 2015. Treatments consisted of 0, 200, and 400μL L⁻¹ chitosan applied to plants grown under field capacity, mild drought stress (50% field capacity), and severe drought stress (25% field capacity). Dry matter yield decreased substantially as drought stress intensified. However, essential oil content increased under stress conditions, with the highest essential oil yield obtained from plants under mild drought stress. Foliar application of chitosan compensated to some extent for dry matter and oil yield reduction of plants grown under drought stress. The highest essential oil yield (1.52g plant⁻¹) was obtained by application of 400μL L⁻¹chitosan under the mild stress condition in 2015 when plants were mature. The compensatory effect of chitosan in reducing the negative impact of stress conditions on dry matter and oil yield was due mainly to stimulation of osmotic adjustment through proline accumulation and reduction of lipid peroxidase level, which increased the integrity of cell membranes of thyme leaves.
The reduction in the precipitation level and the occurrence of frequent drought will be among the top future worries for humans to tackle on this planet. Globally 80% of the agricultural land area is rainfed. According to current research and predictions of frequent drought in the future, there will be a substantial reduction in the economic yield of crop plants, a major threat to food security. Drought tolerance is a major economic consideration to yield. Various biological processes are getting affected by low water stress. Photosynthesis which is an essential biological process for the survival of plants is getting majorly influenced. However, plants have some inbuilt mechanisms to respond to drought stress to some extent. In this mini review, we have highlighted the impact of drought on crop plants, its impact on photosynthesis and responses of plants to drought stress. Understanding mechanism of drought stress tolerance will lead towards development of drought tolerance in crop plants.
Consequences of drought stress in crop production systems are perhaps more deleterious than other abiotic stresses under changing climatic scenarios. Regulations of physio-biochemical responses of plants under drought stress can be used as markers for drought stress tolerance in selection and breeding. The present study was conducted to appraise the performance of three different maize hybrids (Dong Dan 80, Wan Dan 13, and Run Nong 35) under well-watered, low, moderate and SD conditions maintained at 100, 80, 60, and 40% of field capacity, respectively. Compared with well-watered conditions, drought stress caused oxidative stress by excessive production of reactive oxygen species (ROS) which led to reduced growth and yield formation in all maize hybrids; nevertheless, negative effects of drought stress were more prominent in Run Nong 35. Drought-induced osmolyte accumulation and strong enzymatic and non-enzymatic defense systems prevented the severe damage in Dong Dan 80. Overall performance of all maize hybrids under drought stress was recorded as: Dong Dan 80 > Wan Dan 13 > Run Nong 35 with 6.39, 7.35, and 16.55% yield reductions. Consequently, these biochemical traits and differential physiological responses might be helpful to develop drought tolerance genotypes that can withstand water-deficit conditions with minimum yield losses.
Glagah (Saccharum spontaneum L.) has potential value as a crop species and may also be used in sugarcane breeding programs; however, this germplasm has not been extensively used in breeding programs, primarily in relation to improve drought tolerance. The objectives of this experiment were to evaluate the effect of drought stress initiated at vegetative growth stage on growth, leaf proline content and protein pattern of seven glagah accessions (BOT-53, BOT-54, BOT-60, BOT-77, BOT-78, BOT-84, and BOT-88). The plants were propagated from single node stalk segments in polybag in the field under non-stress condition for two months. The two month-old plants were then subjected to drought stress by withholding watering for eight weeks. Untreated control plants were watered every two days. Results indicated that drought stress reduced plant height, stalk diameter and green leaf number. On the other hand, there was a little difference between drought-stressed and control plants in terms of proline content. The protein pattern showed that drought stress caused a change in gene expression in the form of induction or repression of protein expression. A specific protein with a low range of molecular weight (Rf value about 0.647) showed constitutively expressed in accession BOT-53 but drought-inducible expressed in BOT-54.
Keywords: Drought stress, glagah, proline, protein pattern, Saccharum spontaneum
Abscisic acid (ABA), salicylic acid (SA) and γ-aminobutyric acid (GABA) are known to play roles in regulating plant stress responses. This study was conducted to determine metabolites and associated pathways regulated by ABA, SA and GABA that could contribute to drought tolerance in creeping bentgrass (Agrostis stolonifera). Plants were foliar sprayed with ABA (5 μM), GABA (0.5 mM) and SA (10 μM) or water (untreated control) prior to 25 days drought stress in controlled growth chambers. Application of ABA, GABA or SA had similar positive effects on alleviating drought damages, as manifested by the maintenance of lower electrolyte leakage and greater relative water content in leaves of treated plants relative to the untreated control. Metabolic profiling showed that ABA, GABA and SA induced differential metabolic changes under drought stress. ABA mainly promoted the accumulation of organic acids associated with tricarboxylic acid cycle (aconitic acid, succinic acid, lactic acid and malic acid). SA strongly stimulated the accumulation of amino acids (proline, serine, threonine and alanine) and carbohydrates (glucose, mannose, fructose and cellobiose). GABA enhanced the accumulation of amino acids (GABA, glycine, valine, proline, 5-oxoproline, serine, threonine, aspartic acid and glutamic acid) and organic acids (malic acid, lactic acid, gluconic acid, malonic acid and ribonic acid). The enhanced drought tolerance could be mainly due to the enhanced respiration metabolism by ABA, amino acids and carbohydrates involved in osmotic adjustment (OA) and energy metabolism by SA, and amino acid metabolism related to OA and stress-defense secondary metabolism by GABA.
Drought is one of the major constraints limiting crop production worldwide. Crop growth models predict that this issue will be more severe in future. Drought impairs normal growth, disturbs water relations, and reduces water use efficiency in plants. Plants, however, have a variety of physiological and biochemical responses at cellular and whole organism levels, making it a more complex phenomenon. The rate of photosynthesis is reduced mainly by stomatal closure, membrane damage, and disturbed activity of various enzymes, especially those involved in ATP synthesis. Plants display a range of mechanisms to withstand drought, such as reduced water loss by increased diffusive resistance, increased water uptake with prolific and deep root systems, and smaller and succulent leaves to reduce transpirational loss. Low-molecular-weight osmolytes, including glycinebetaine, proline and other amino acids, organic acids, and polyols also play vital roles in sustaining cellular functions under drought. Plant growth substances such as salicylic acid, auxins, gibberellins, cytokinins, and abscisic acid modulate plant responses toward drought. Polyamines, citrulline, and several enzymes act as antioxidants and reduce adverse effects of water deficit. Plant drought stress can be managed by adopting strategies such as mass screening and breeding, marker-assisted selection, and exogenous application of hormones and osmoprotectants to seeds or growing plants, as well as engineering for drought resistance. Here, we provide an overview of plant drought stress, its effects on plants’ resistance mechanisms and management strategies to cope with drought stress.
Reactive oxygen species (ROS) were initially recognized as toxic by-products of aerobic metabolism. In recent years, it has become apparent that ROS plays an important signaling role in plants, controlling processes such as growth, development and especially response to biotic and abiotic environmental stimuli. The major members of the ROS family include free radicals like O•−2, OH• and non-radicals like H2O2 and ¹O2. The ROS production in plants is mainly localized in the chloroplast, mitochondria and peroxisomes. There are secondary sites as well like the endoplasmic reticulum, cell membrane, cell wall and the apoplast. The role of the ROS family is that of a double edged sword; while they act as secondary messengers in various key physiological phenomena, they also induce oxidative damages under several environmental stress conditions like salinity, drought, cold, heavy metals, UV irradiation etc., when the delicate balance between ROS production and elimination, necessary for normal cellular homeostasis, is disturbed. The cellular damages are manifested in the form of degradation of biomolecules like pigments, proteins, lipids, carbohydrates, and DNA, which ultimately amalgamate in plant cellular death. To ensure survival, plants have developed efficient antioxidant machinery having two arms, (i) enzymatic components like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR); (ii) non-enzymatic antioxidants like ascorbic acid (AA), reduced glutathione (GSH), α-tocopherol, carotenoids, flavonoids, and the osmolyte proline. These two components work hand in hand to scavenge ROS. In this review, we emphasize on the different types of ROS, their cellular production sites, their targets, and their scavenging mechanism mediated by both the branches of the antioxidant systems, highlighting the potential role of antioxidants in abiotic stress tolerance and cellular survival. Such a comprehensive knowledge of ROS action and their regulation on antioxidants will enable us to develop strategies to genetically engineer stress-tolerant plants.
Seedling period is an important stage of plant growth. This research was mainly to analysis the influence of chitosan on wheat seedling growth and physiological mechanisms under drought stress. The results showed that the group coated with chitosan significantly improved the growth index such as germination rate, wet weight, root length, root active, and impacted physiological indices such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT)), the content of malwondialdehyde (MDA) and chlorophyll compared with CK under drought stress. Activities of POD, CAT and SOD increased and then decreased, the content of MDA increased under drought stress. But. variation rates of the group coated with chitosan were slower than that of CK, which indicates that chitosan can significantly improve anti-oxidant enzymes activity to clear timely active oxygen and reduce the content of MDA so as to alleviate the degree of damage in the drought stress and make seedlings grow better. The results also showed that chitosan improved chloro-phyll content than that of CK, which demonstrated that chlorophyll content significantly influenced the photosynthetic efficiency of the mutant and added wheat above ground biomass and the field experiment results showed that chitosan increased yield 13.6% than that of CK.
Water stress impaired cowpea plant growth and decreased ion percentage and chlorophyll and carbohydrate concentration in the shoot as well as yield and its quality. Foliar-applied chitosan, in particular 250 mg/l, increased plant growth, yield and its quality as well as physiological constituents in plant shoot under stressed or nonstressed conditions as compared to untreated plants. Anatomically, water stress decreased thickness of leaf blade at midrib region, thickness of mesophyll tissue, thickness of midrib vascular bundle. Treatment with chitosan, in particular, 250 mg/l and their interactions with stress conditions increased all the above mentioned parameters in either non-stressed or stressed plants. It is suggested that the severity of cowpea plants damaged from water stress was reduced by 250 mg/l chitosan application.
Perovskia abrotanoides Karel. is a medicinal plant used in Iranian folk medicine as a pain killer. Forty-one components have been identified in P. abrotanoides samples collected from Baluchistan Province, and 29 components have been recognized in samples collected from Khorasan Province. The leaves of P. abrotanoides have glandular trichomes (capitates and peltate) on both sides of the lamina.
This study aimed to evaluate the variation of oil constituents of the plant and illustrate the glandular trichomes types and then show the influence of environment on oil constituents and glandular trichomes.
The essential oil of the plant was obtained using hydrodistillation and the analysis of oils carried out using GC-MS. The anatomical analysis of leaves was done by fixing, coloring, and photoing the sections.
Glandular trichomes composed of capitates and peltate trichomes. The essential oil composition differs. Viridiflora and neryl acetate were not identified in yellow glandular trichomes.
It seems that there is no relation between anatomical characteristics of the plant leaves and its essential oil composition.
The present study was conducted to evaluate the proliferation ability of M26 apple rootstock on the MS medium supplemented with various concentrations of crab chitosan, gibberellic acid (GA3), and N6-benzyladenine (BA). Combination of 120 mg·L −1 chitosan and 0.5 mg·L −1 BA in the absence of GA3 was most suitable for the proliferation after 12 weeks. Without chitosan, total number of shoots increased by increasing BA concentration, but the shoots led to rosette and dense growth, developing tiny yellowish leaves with soft and watery tissues. Shoots taller than 3 cm were obtained by 0.1 or 0.3 mg·L −1 GA3 in combination with 120 mg·L −1 chitosan, but leaves were small with yellowish green color. These results indicated that chitosan can be used as a growth stimulator in combination with a minor amount of plant growth regulators to improve the proliferation rate of in vitro cultured M26 apple rootstock.
Kaposi sarcoma-associated herpesvirus (KSHV) is the etiologic agent for Kaposi Sarcoma (KS), the most common cancer diagnosed in HIV- infected patients. The role of neutralizing antibodies in KS pathogenesis and in KSHV infected individuals is not clearly understood. The goal of this study was to investigate and compare the prevalence and titers of neutralizing antibodies in plasma samples from KS patients and KSHV infected asymptomatic individuals from Zambia, a KS endemic region in sub-Saharan Africa. Plasma samples (N = 267) consisting of KS patients (group 1) and asymptomatic individuals (group 2) were collected from Lusaka, Zambia. A flow cytometry based quantitative neutralization assay utilizing recombinant KSHV expressing GFP was used to detect KSHV neutralizing antibodies. Our results show that the overall prevalence of neutralizing antibodies in KS patients (group 1) was 66.7% which was significantly higher than the prevalence of 6.5% present in KSHV infected asymptomatic individuals (group 2). Total antibody titers as well as neutralizing antibodies titers were found to be significantly higher among KS patients. It is likely that higher neutralizing antibodies prevalence and titers in KS patients result from higher levels of antigenic stimulation over time. This study is first to compare prevalence and titers of neutralizing antibodies in participants with and without disease from a KSHV endemic region.
Salinity and water-deficit stress reduce yield in agricultural crops. On the other hand, seed germination is critical in seedling establishment and subsequent plant growth. Therefore, the present investigation was carried out to evaluate the effects of chitosan (Ch) concentrations (0% [control], 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 1%, 2%, and 3%) on the tolerance of safflower (Carthamus tinctorius L.) to different osmotic potentials (0, −0.4, −0.8, and −1.2 MPa). Induced osmotic potential significantly decreased germination percentage, germination index and rate, length and weight of root and shoot, and protein content. Proline content, malondialdehyde content (MDA), and catalase (CAT) and peroxidase (POX) activity increased when osmotic potential was increased to −0.8 MPa. Under unstressed conditions (0 MPa), there were no significant differences in germination percentage among different concentrations of chitosan, whereas MDA content, CAT, and POX activity were increased by low concentrations of chitosan (0.05%–0.4%). With increasing water-deficit stress, low concentrations of chitosan increased germination percentage but decreased MDA and proline contents and CAT and POX activity. Thus, it could be concluded that low concentrations of chitosan exhibited positive effects on water-deficit alleviation through the reduction of enzyme activity. Therefore, chitosan should be an effective biostimulator to enhance seedling growth and plant tolerance to oxidative stress conditions, especially under conditions of drought stress.
Two cultivars of peanut (Arachis hypogaea L.) which were designated as resistant (Florispan) and sensitive (Gazipasa) according to their growth retardation under drought stress conditions were compared for their oxidative damage and antioxidant responses. Sixteen days-old peanut seedlings were subjected to PEG-6000 solutions of two different osmotic potentials; −0.4 and −0.8 MPa, and various growth parameters, photosystem II activity, changes in malondialdehyde (MDA), hydrogen peroxide (H2O2) and proline levels, activities of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX) and gluthatione reductase (GR) enzymes were determined. Both cultivars exhibited water deficit at −0.8 MPa osmotic potential of PEG-6000 and H2O2 levels significantly increased during exposure to −0.4 MPa osmotic potential. However, H2O2 levels were under control in both cultivars at exposure to −0.8 MPa osmotic potential. Significant proline accumulation was observed in the tissues of cv. Florispan at −0.8 MPa osmotic potential, whereas proline accumulation did not appear to be an essential part of the protection mechanism against drought in cv. Gazipasa. No significant variation in chlorophyll fluorescence values were detected in neither of the cultivars. Enzyme activity measurements revealed that Gazipasa copes well with lesser magnitudes of drought stress by increasing the activity of mainly APX, and during harsh stress conditions, only APX maintains its activity in the tissues. In cultivar Florispan, GR activity appears to take role in lesser magnitudes of drought stress, whereas CAT and APX activities appear to be very crucial antioxidative defenses during intense stress conditions. The results indicate that, the level of proline and activities of the enzymes CAT and APX are important mechanisms for the maintenance of drought tolerance in peanut plants.
The objective of this study was to evaluate the changes in the chemical composition of essential oils (EO) and the correlation between some secondary metabolites and antioxidant activity of different plant parts of Perovskia abrotanoides Kar. at the vegetative and flowering stages in Vamnan (Iran) in 2018. The EO of this plant was analyzed using the GC-Mass Spectrometry method. As the findings showed, P. abrotanoides leaf, during the flowering stage, had a greater amount of phenolic compounds, flavonoids, and anthocyanins than other parts and even the vegetative stage. At the flowering stage, the maximum antioxidant activity was obtained in the leaf (69.10%), based on the DPPH method. During the vegetative stage, the root was also in the next rank (62.10%). In this research, aerial parts of P. abrotanoides were different in terms of EO composition percentage and retention time. Likewise, 21 and 26 constitutes were identified during the vegetative and flowering stages, respectively. The major constitute was Carotol (31.105%) at the flowering stage, where IR-alpha-pinene (0.268%) had the lowest value. Overall, the results showed that P. abrotanoides can be introduced as an important source of natural antioxidant for pharmaceutical and natural food supplements due to its acceptable amount of bioactive compounds such as phenolic, flavonoids, anthocyanins, and EO. © 2021, National Institute of Science Communication and Information Resources. All rights reserved.
Drought is a main abiotic stress that restricts plant growth and development. The increased global demand of anti-cancer alkaloids extracted from periwinkle (Catharanthus roseus) is mainly related to plant growth and development, which are severely affected by drought. Chitosan nanoparticles (CSNPs) have been used to boost plant growth and defense mechanism, however their impact to alleviate drought stress of C. roseus has not been investigated yet. In this study, control and stressed plants (100 and 50 % of field capacity [FC], respectively) were subjected to CSNPs application at 1%. Drought stress considerably reduced plant growth, relative water content (RWC), stomatal conductance and total chlorophyll; however, CSNPs mitigated these effects. They enhanced proline accumulation and the activity of catalase (CAT) and ascorbate peroxidase (APX) with possible mitigation of drought-induced oxidative stress. Therefore, they reduced H2O2 and malondialdehyde (MDA) accumulation, and eventually preserved membrane integrity. Drought stress increased alkaloid accumulation, and further increase was observed with the application of CSNPs. High alkaloid content was associated with induced gene expression of strictosidine synthase (STR), deacetylvindoline-4-O-acetyltransferase (DAT), peroxidase 1 (PRX1) and geissoschizine synthase (GS) up to 5.6 folds under drought stress, but more accumulation was noticed with the application of CSNPs. Overall, this study is the first on using CSNPs to mitigate drought stress of C. roseus by inducing the antioxidant potential and gene expression of alkaloid biosynthesis.
Gas chromatography–mass spectrometry analysis together with principal component analysis revealed that geographical origin influenced the yield and composition of the essential oils (EOs) extracted by hydrodistillation performed for 3 h using a Clevenger-type apparatus, from the cones of Cedrus libani A. Rich., growing wild at four Lebanese natural reserves and protected areas: Bsharri, Chouf, Ehden, and Tannourine, and from a cultivated cedar growing in Qartaba. Essential oil chemical variability established between the different studied provenances suggested the involvement of abiotic factors such as geographical conditions, cultivation conditions, soil composition, and environmental factors in the chemical polymorphism of C. libani cones EOs. α-Pinene/β-pinene characterized Ehden (β-pinene 35.6%/α-pinene 27.7%), Chouf (α-pinene 37.3%/β-pinene 26.1%), Bsharri (α-pinene 27.7%/β-pinene 21.4%), and Tannourine (α-pinene 25.1%/β-pinene 16.0%) samples, whereas Qartaba EO was distinguished by the dominance of myrcene (30.6%), α-pinene(26%), and limonene (14.1%). Comparison with the existing literature reinforced the chemical variability of C. libani EOs. This current study helped the estimation of a best harvest location for a good EO quality production, resource optimization, and pharmacological properties evaluation, according to the market demand.
The essential oils and antioxidant activity of four Thymus species were evaluated under five light spectra (namely, red, blue, red-blue, white, and greenhouse condition). The highest essential oil yield (4.17%) was observed under red light in T. migricus, while the lowest (1.05%) was observed in T. carmanicus under greenhouse conditions. Light quality also led to difference in essential oil constituents. The highest thymol (66%) was found in T. migricus exposed to blue light, while the least (1.69%) was observed in T. kotschyanus grown under red-blue light. The LED treatments did not induce any significant effect on carvacrol of Thymus species in comparison to the greenhouse condition. Finally, the analysis of variance indicates that the effect of light varied with the studied species. T. migricus performed the highest antioxidant capacity (IC50 = 176.8 µg/mL) under blue light. Overall, essential oil components as well as antioxidants showed significant responses to light emitting diodes wavelengths.
Chitosan in both native and degraded form (oligosaccharides) acts as a growth promoter and generate responses associated with both primary and secondary metabolism in plants. Chitosan and its oligosaccharides enhance photosynthesis by amplifying the activities of various enzymes of carbon and nitrogen metabolism as well as light and dark reaction of photosynthesis. They play a vital role in stimulating photosynthetic machinery by regulating primary photochemistry. They also overcome the limitations of stomata and amplify the carbon fixation efficiency in dark reactions and promote carbohydrate synthesis. Chitosan and its oligosaccharides stimulate the enzymes and content of secondary metabolites. A plausible explanation is that chitosan and its oligosaccharides acted as the suitable ligand for the induction of available receptors and thus elicit various signaling pathways viz, GPCR and PLC/PKC, MAPK, H2O2 burst, stimulation of transcription factors in the plant generating a maximum possible response. Chitosan and its oligosaccharides also exhibit antimicrobial activities and act as biopestiside, preventing proliferation of pathogens and preserve crop yield and quality.
Sage (Salvia officinalis L.), which is one of the most important pharmaceutical herbs, has been exploited for many uses. It is an important industrial crop that natural products in the form of extracts and essential oil from the leaves of this herb are used in pharmaceutical, perfumery, and food industries. Response of sage to foliar application of chitosan (control, 0.0, 0.25 and 0.50 g/L), a marine polysaccharide with unique bioactive properties, under three irrigation frequencies (4, 6, and 8 every days) was evaluated in an experimental field at semiarid and cold climate, Southwestern of Iran. Chitosan and irrigation frequencies treatments had significant effects on studied parameters, including quantity and quality of essential oil, antioxidant activities, and the amounts of total phenolic and flavonoids of the extract of sage. The results clearly indicated that application of chitosan was beneficial to plants under deficit irrigation treatments. The foliar application of chitosan reduced the adverse effect of reduced irrigation on essential oil yield and improved content of the essential oil. Elicitation of sage with chitosan had positive influences on the amounts of secondary metabolites, such as α-pinene, β-pinene, limonene, α-thujone, β-thujone, camphor, and 1,8-cineole in the essential oil from sage under reduced irrigation. In reduced irrigation conditions, the antioxidant activity, and the amounts of total phenolic and flavonoid of the extracts increased when the plants were sprayed with chitosan. In conclusion, results of this study indicated that the spray of chitosan elicitor can be have useful impacts on the essential oil quality and quantity, antioxidant activity, and the amounts of total phenolic and flavonoid of sage under reduced irrigation conditions or drought stress.
Drought tolerance is a complex trait that involves different biochemical and physiological mechanisms in plants. It was the objective of the present study to evaluate the agronomic and biochemical responses of triticale, tritipyrum, and wheat to drought stress. For this purpose, twenty-seven genotypes were evaluated under two levels (non-stress and drought stress) of irrigation during 2015‒2017. The metabolic traits studied included relative water content (RWC), membrane stability index (MSI), chlorophyll a (Chla), chlorophyll b (Chlb), carotenoids (Car), leaf proline content (Pro), leaf soluble carbohydrates (LSC), glycine betaine (GB), malondialdehyde (MDA), hydrogen peroxide (H2O2), seeds per spike (SS), seed weight (SW), biological yield (BY) and seed yield (SY). Drought stress increased Pro, LSC, and GB contents as well as lipid peroxidation through increasing MDA and H2O2 activities. However, both RWC and MSI indices as well as SS, SW, SY and BY reduced as a result of drought treatment although the least decrease of SY was observed at triticale group. During the two years of study, the tritipyrum genotypes exhibited their drought tolerance by accumulation of more LSC and GB as well as lower decrease in SW while the triticale ones responded by maintaining higher levels of RWC but producing less MDA and H2O2. It may, therefore, be concluded that the three species studied exploit different mechanisms to maintain tolerance against drought stress. Finally, correlation analysis indicated the positive effects of LSC on SY under both drought and normal conditions, which is obviously a promising trait in wheat, triticale, and tritipyrum that can be beneficially exploited in drought tolerance improvement programs.
Genetic and the essential oil composition variability among twelve Perovskia abrotanoides populations (PAbPs) growing wild in Iran were assessed by ISSR markers, GC–FID and GC–MS, respectively. Nine selected ISSR primers produced 119 discernible bands, of them 96 (80.7%) being polymorphic. Genetic similarity values among populations ranged between 0.07 and 0.79 which indicated a high level of genetic variation. Polymorphic information content, resolving power and marker index generated by ISSR primers were, 0.31, 6.14 and 3.32, respectively. UPGMA grouped PAbPs into four main clusters. Altogether, 38 chemical compounds were identified in the oils, and a relatively high variation in their contents was found. Camphor (11.9-27.5%), 1,8-cineole (11.3-21.3%), α-bisabolol (0.0-13.1%), α-pinene (5.9-10.8%) and δ-3-carene (0.1-10.5%) were the major compounds. Oxygenated monoterpenes (32.1-35.8%) and monoterpene hydrocarbons (25.7-30.4%) were the main groups of compounds in the oils studied. Cluster analysis and principal-component analysis were used to characterize the samples according to oil components. Four main chemotypes were found to be Chemotype I (camphor/1,8-cineol), Chemotype II (1,8-cineole/camphor), Chemotype III (camphor/1,8-cineol/α-bisabolol), and Chemotype IV (camphor/δ-3-carene/α-bisabolol). The information provided here, on P. abrotanoides populations will be useful to introduce this plant into agricultural systems. This article is protected by copyright. All rights reserved.
Origanum vulgare, a popular flavoring herb, is valued for several biological properties. The present study focused on the chemical composition and antioxidant activity of the essential oils of Origanum vulgare subsp. gracile in different plant parts and at different phenological stages. Qualitative and quantitative analyses of the essential oil identified 41 constituents that varied with plant age and organ. The phenolic monoterpenoid carvacrol (18.1–79.2%) was predominant in all the essential oil samples. Other major constituents were p-cymene (3.9–18.0%), γ-terpinene (0.9–15.8%), carvacrol methyl ether (0.8–9.9%), and (Z)-α-bisabolene (0.5–8.7%). Among the different plant parts and phenological growth stages, the highest levels of carvacrol were identified in the essential oils from flowers (79.2%), roots (70%), and the early vegetative growth (67.34%). All the essential oils exhibited high radical-scavenging properties as shown in the DPPH* assay. The essential oils from flowers, however, exhibited the highest antioxidant activity and could be used as a preservative agent on an industrial scale.
The experiment was carried out with plants grown in pots with soil to determine the effects of different levels of water stress on roots biomass, secondary metabolites in roots and endogenous hormones (IAA, GA3 and ABA), relative water content (RWC), tissue density (TD) in leaves of Stellaria dichotoma L.var. lanceolata Bge. The results showed that roots biomass, total saponins content firstly increased and then decreased with increasing water stress levels. RWC significantly decreased with increasing water stress levels while the change of TD was inverse. The concentration of IAA and GA3 firstly increased and then decreased with increasing water stress levels and reached maximum value under 60–70% of field capacity (FC). However, ABA concentration sharply increased under ≤40–50% FC. With correlation analysis and principal component analysis (PCA), total flavonoids content had significant positive with ABA and TD, but had a negative correlation with RWC. Roots biomass had a significant negative correlation with ABA, while ABA had a very significant negative correlation with RWC and a significant positive correlation with TD. The PCA partitioned the total variance into 2 PCs contributing maximum (90.793%) to the total diversity among the water stress due to the study of various traits. The higher eigenvector of PC I is RWC and ABA, whereas the higher and positive eigenvector of PC II is GA3, total saponins content and IAA. Our study indicated that roots biomass and secondary metabolites of S. dichotoma were first increases and then decreases with increasing water stress levels. Thus, moderate water stress (60–70% or 80–90% FC) was suitable for roots biomass formation and active ingredient accumulation, which was affected by endogenous hormones and water status.
The last estimated annual incidence of Trichomonas vaginalis worldwide exceeds that of chlamydia and gonorrhea combined. This critical review updates the state of the art on advances in T. vaginalis diagnostics and strategies for treatment and prevention of trichomoniasis. In particular, new data on treatment outcomes for topical administration of formulations are reviewed and discussed.
Chitosan is a biopolymer with various industrial, medicinal, pharmaceutical, and agricultural applications. Effects of exogenous application of chitosan, a marine polysaccharide with unique bioactive properties, under normal irrigation and stressed conditions on morphology, physiology and biochemical characteristics of two species of sweet basil, including Ocimum ciliatum and O. basilicum in a pot experimental at semiarid and cold climate, southwestern Iran were investigated. Treatments comprised control, 0.0, 0.2, and 0.4 g/L chitosan applied to plants under normal irrigation, slight and mild drought stress conditions. Results indicated that drought stress had significant effects on some morphology, physiology and biochemical characteristics. In both species of basil, drought stress decreased the content of photosynthetic pigments and growth parameters. Exogenousapplication of chitosan (in particular 0.4 g/L) increased plant growth parameters in both species of basil under stressed or non-stressed conditions as compared to untreated plants. In addition, results indicated that the different levels of chitosan had significant effects on total phenol content and antioxidant activity of the extracts of two species. In conclusion, it is suggested that chitosan could be a promising material used to reduce the harmful effect of water stress on the growth parameters of basil plants and as a whole, treatment with chitosan partly could alleviate the effect of drought stress.
Under field conditions crops are routinely subjected to a number of different abiotic stress factors simultaneously. Recent studies revealed that the response of plants to a combination of different abiotic stresses is unique and cannot be directly extrapolated from simply studying each of the different stresses applied individually. These studies have also identified specific regulatory transcripts, combinations of metabolites and proteins, and physiological responses that are unique to specific stress combinations, highlighting the importance of studying abiotic stress combination in plants. Here we describe the interactions between drought and other abiotic stresses with emphasis on drought and heat stress. We compile new data about the different molecular, physiological and metabolic adaptations of different plants and crops to this stress combination and we highlight the importance of reactive oxygen species (ROS) metabolism and stomatal responses for plant acclimation to drought and heat stress combination. We further emphasize the need for developing crops with enhanced tolerance to drought and heat stress combination in order to mitigate the negative impacts of predicted global climatic changes on agricultural production worldwide.
Mild and moderate plant water stress increased sweet basil leaf essential oil content and altered oil composition. After 21 d of plant water deficit, the oil content of leaves increased from 3.1 to 6.2 μl.g1 leaf dry wt. as xylem water potential (ψ) decreased from −0.30 to −1.12 MPa. Significant decreases in leaf dry weight and stem dry weight were observed as plant water deficit increased. Only leaf area from plants subjected to a mild water deficit (-0.68 MPa) was not significantly reduced compared to the control, non-stressed plants.Water stress altered the oil composition (both as a relative percentage of total oil and μl.g leaf dry weight). Linalool and methyl chavicol increased as water stress increased, while the relative proportion of sesquiterpenes decreased.
Cryptotanshinone (1), a quinoid diterpene with a nor-abietane skeleton, and three new natural products, 1 beta -hydroxycryptotanshinone (2), 1-oxocryptotanshinone (3), and 1-oxomiltirone (4), were isolated from roots of the Iranian medicinal plant Perouskia abrotanoides. Their structures were established using homo- and heteronuclear two-dimensional NMR experiments, supported by HRMS. The total amount of tanshinones isolated from dry roots of Perovskia abrotanoides was about 1.5%. The compounds exhibited leishmanicidal activity in vitro (IC50 values in the range 18-47 muM). These findings provide a rationale for traditional use of the roots in Iran as a constituent of poultices for treatment of cutaneous leishmaniasis. The isolated tanshinones also inhibited growth of cultured malaria parasites (3D7 strain of Plasmodium falciparum), drug-sensitive KB-3-1 human carcinoma cell line, multidrug-resistant KB-V1 cell line, and human lymphocytes activated with phytohaemagglutinin A (IC50 values in the range 5-45 muM). The toxicity of tanshinones toward the drug-sensitive KB-3-1 and the multidrug-resistant KB-V1 cells was the same, indicating that the compounds are not substrates for the P-glycoprotein drug efflux pump.