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Chemical structures of phytohormones and roles they play in plant growing in adverse conditions, such as water and salt stresses. These compounds are multifunctional molecules playing several different roles in plant responses.
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The phytohormones are pivotal chemical messengers produced within the plant that regulate its
growth and development, and responses to environmental stimuli. Drought and salinity are adverse
environmental factors that disturb the plant hormonal balance. Accordingly, these hormonal
fluctuations modify the cellular dynamic and hence they play a centr...
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... various tolerance me- chanisms have been described on the basis of physiological modifications to overcome the harmful effects of drought and salt stresses. Among them, one of the most important is the alteration in endogenous phytohormone levels (Figure 1). It is well established that plant hormones modulate several responses during the whole plant life cycle both under stress and non-stress conditions [6]. ...
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... The hormone system plays a crucial role in plant development and the ability of plants to adapt to environmental stress [16]. The adaptation of plants to stress is closely linked to the balance of endogenous plant hormones [17]. GA, as an endogenous signalling molecule for breaking seed dormancy, can directly promote the synthesis of endogenous GA, regulate the metabolism of substances and the degradation of storage substances and synergistically regulate seed germination, which is currently one of the most effective methods for regulating seed dormancy [18]. ...
Polyethylene glycol can abrogate plant seed dormancy and alleviate salt–alkali stress damage to plants, but its role in embryonic dormancy abrogation and germination in Sorbus pohuashanensis is not yet clear. The mechanism by which polyethylene glycol promotes the release of embryonic dormancy may be related to the synthesis and metabolism of endogenous hormones, reactive oxygen species and reactive nitrogen. In this article, germination in indoor culture dishes was used, and the most suitable conditions for treating S. pohuashanensis embryos, with polyethylene glycol (PEG) and sodium carbonate (Na2CO3), were selected. Germination was observed and recorded, and related physiological indicators such as endogenous hormones, reactive oxygen species and reactive nitrogen were measured and analyzed to elucidate the mechanism of polyethylene glycol in alleviating salt–alkali stress in S. pohuashanensis embryos. The results showed that soaking seeds in 5% PEG for 5 days is the best condition to promote germination, which can increase the germination rate of embryos under salt–alkali stress by 1–2 times and improve indicators such as germination speed and the germination index. Polyethylene glycol led to an increase in gibberellin (GA), indole-3-acetic acid (IAA), ethylene (ETH), cytokinin (CTK), nitric oxide (NO), soluble protein and soluble sugar in the embryos under salt–alkali stress; increased activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), nitrate reductase (NR) and nitric oxide synthase (NOS) in the embryos; a reduction in the accumulation of abscisic acid (ABA), hydrogen peroxide (H2O2) and malondialdehyde (MDA). Therefore, it is suggested that the inhibitory effect of polyethylene glycol on the salt–alkali-stress-induced germination of S. pohuashanensis embryos is closely related to the response of endogenous hormones, reactive oxygen species and nitric oxide signalling.
... These processes include improvement in root system, leaf structure, osmotic adjustment, hydric relation and modifications in the metabolism of organic compounds like carbohydrates, amino acids and hormones. Plant hormones are crucial to counteract drought stress, maintain growth, and raise the likelihood of survival in adverse conditions (Llanes et al. 2016;Ullah et al. 2018). Recent studies in the field of metabolic engineering have found that phytohormones including abscisic acid, auxins, cytokinins ethylene and gibberellins, as well as newer members such as brassinosteroids, jasmonates and strigolactones, may be significant in the design of abiotic stress-tolerant crops. ...
... The endogenous content of auxins (IAA) and jasmonic acid (JA) also increased in our plants when subjected to water stress, and the highest levels were recorded in the shoots. Previous studies have described the intervention of these hormones in the regulation of plant development and growth (Llanes et al. 2016;Shukla et al. 2019). IAA is involved in cell division, foliar senescence, nutrient mobilization, apical dominance, and the differentiation of chloroplasts. ...
With increasing economic and nutritional demands that far outpace the addition of new agricultural areas around the world, biofertilizers are increasingly used to ensure the productivity of existing areas without sacrificing sustainability. This study evaluated the combination of algal extracts of Macrocystis pyrifera (a natural biofertilizer) with the plant growth-promoting bacteria Azospirillum argentinense in terms of their effectiveness in stimulating germination and growth of maize plants under different irrigation conditions. The performance of maize plants inoculated with the algae-bacteria formulation under water stress conditions was evaluated. The variables studied included different germination and growth parameters, such as dry and fresh weight of aerial and root part, total height and aerial and root part. The hormonal profile in maize seedlings was determined. The results related to growth parameters and phytohormone content demonstrate a synergistic effect between algae and bacteria, which means that a bioinoculant could be formulated based on their combination to promote the growth of maize in different climatic conditions and/or or water regimes. Such a product would fit well into current or future environmentally friendly plans for growing maize, aiming to reduce dependence on chemical fertilizers while preserving yield.
... Some phytohormones, notably ABA, JA, SA, and ethylene, have been shown to either independently or synergistically manage drought responses in plants [4,42,65,66]. ABA, in particular, is a crucial stress-signalling hormone that increases in concentration during drought stress periods, acting as the primary hormonal signalling agent for plants under water stress conditions [67,68]. Our current study revealed differential expression of two significant genes associated with ABA signal transduction, phosphatase 2C (PP2C) and serine/threonineprotein kinase (SAPK), between RhMED15a-like-silenced rose and TRV controls (Table 1). ...
Background
Rose (Rosa hybrida) is a globally recognized ornamental plant whose growth and distribution are strongly limited by drought stress. The role of Mediator, a multiprotein complex crucial for RNA polymerase II-driven transcription, has been elucidated in drought stress responses in plants. However, its physiological function and regulatory mechanism in horticultural crop species remain elusive.
Results
In this study, we identified a Tail module subunit of Mediator, RhMED15a-like, in rose. Drought stress, as well as treatment with methyl jasmonate (MeJA) and abscisic acid (ABA), significantly suppressed the transcript level of RhMED15a-like. Overexpressing RhMED15a-like markedly bolstered the osmotic stress tolerance of Arabidopsis, as evidenced by increased germination rate, root length, and fresh weight. In contrast, the silencing of RhMED15a-like through virus induced gene silencing in rose resulted in elevated malondialdehyde accumulation, exacerbated leaf wilting, reduced survival rate, and downregulated expression of drought-responsive genes during drought stress. Additionally, using RNA-seq, we identified 972 differentially expressed genes (DEGs) between tobacco rattle virus (TRV)-RhMED15a-like plants and TRV controls. Gene Ontology (GO) analysis revealed that some DEGs were predominantly associated with terms related to the oxidative stress response, such as ‘response to reactive oxygen species’ and ‘peroxisome’. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment highlighted pathways related to ‘plant hormone signal transduction’, in which the majority of DEGs in the jasmonate (JA) and ABA signalling pathways were induced in TRV-RhMED15a-like plants.
Conclusion
Our findings underscore the pivotal role of the Mediator subunit RhMED15a-like in the ability of rose to withstand drought stress, probably by controlling the transcript levels of drought-responsive genes and signalling pathway elements of stress-related hormones, providing a solid foundation for future research into the molecular mechanisms underlying drought tolerance in rose.
... Так, за дії негативних чинників синтез гіберелінів пригнічується внаслідок експресії генів GA2ox, які кодують GA2-інактивуючі ензими, а також гена DELLA RGL3, який кодує супресор росту [42]. Мутантні лінії зі зниженим вмістом гіберелінів проявляли соле-і посухостійкість завдяки зменшенню біосинтезу або посиленню деградації гормону [44]. У коренях емеру Triticum turgidum ssp. ...
PHYTOHORMONES IN GROWTH REGULATION AND THE FORMATION OF
STRESS RESISTANCE IN CULTIVATED CEREALS
I.V. Kosakivska, M.M. Shcherbatiuk, V.A. Vasyuk, L.V. Voytenko
M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine
2 Tereshchenkivska St., Кyiv, 01004, Ukraine
e-mail: chrom.botany@ukr.net
The study of abiotic stresses’ impact on the growth, development and productivity of cultivated
cereals stands as one of the principal tasks of modern biological science. In response
to stressors, plants modify their developmental pathway through morphological, physiological
and biochemical reactions, thereby alleviating stress loads, limiting damage, and facilitating recovery processes. Phytohormones play a pivotal role in regulating all stages of the
plant life cycle — from seed germination to senescence — under both optimal and stressful
conditions. They serve as signaling triggers, initiating cascade of reactions that aid plants in
adapting to adverse influences. Therefore, determining their content and localization sites is
important for finding ways to control growth rate, development, and stress resistance formation.
Among phytohormones, abscisic acid (ABA) is extensively studied for its involvement
in responses to abiotic stresses. Stress-induced ABA accumulation, as a mechanism for
slowing down metabolism, enables plants to adapt to adverse factors. Cytokinins and auxins
also contributed significantly to the formation of adaptive plant responses, with stressinduced
changes in their content and distribution being observed in numerous plant species.
Gibberellins are closely associated with crucial developmental processes, making them essential
for the precise implementation of plant genetic programs. The mechanism of stress resistance
formation involving salicylic acid remains complex and not entirely understood. This
hormone enhances osmolyte production, antioxidant activity, and interacts with other hormones.
A promising strategy to increase the stability and yield of cultivated cereals involves
the exogenous application of phytohormonal treatments, which effectively mitigate negative
effects. Pre-sowing priming provides optimal conditions for initiating the metabolic processes
during germination, minimizing seed quality and structure problems, and ensuring uniform,
strong seedlings. Priming triggers metabolic processes that enhance growth and
prompts alteration in the balance and distribution of endogenous hormones within plant
organs. However, the mechanisms through which priming with exogenous phytohormones
enhances seed germination, subsequent plant growth, and development remained insufficiently
explored and not entirely understood. This review delves into recent advancements
concerning the roles of both endogenous and exogenous phytohormones in regulating growth
and promoting resistance to abiotic stresses in cultivated cereals.
Key words: cultured cereals, phytohormones, growth, stress resistance, signaling systems.
... 1). Вместе с тем хорошо известно, что в неблагоприятных условиях, в частности при нарушении водного режима, происходят существенные перестройки в гормональном балансе растений, характеризующиеся резким повышением концентрации гормона стресса -абсцизовой кислоты и снижением количества ростостимулирующих гормонов ауксинов и цитокининов (17,23,26). ...
... 1). Вместе с тем хорошо известно, что в неблагоприятных условиях, в частности при нарушении водного режима, происходят существенные перестройки в гормональном балансе растений, характеризующиеся резким повышением концентрации гормона стресса -абсцизовой кислоты и снижением количества ростостимулирующих гормонов ауксинов и цитокининов (17,23,26). ...
... 29 Recently, it became evident that phytohormone changes are closely associated with yield production and adaptation to environmental conditions in crop plants. [30][31][32][33] In addition, a report revealed that the introduction of Lonicera japonica, a traditional Chinese medicinal plant, from the geo-authentic areas to nonauthentic production areas resulted in significant changes of various phytohormones in flower buds, which altered its medicinal quality. 34 It will be of significance to understand the part of cAMP to modulate phytohormones in crop plants for improving productivity and quality. ...
In higher plants, the regulatory roles of cAMP (cyclic adenosine 3′,5′-monophosphate) signaling remain elusive until now. Cellular cAMP levels are generally much lower in higher plants than in animals and transiently elevated for triggering downstream signaling events. Moreover, plant adenylate cyclase (AC) activities are found in different moonlighting multifunctional proteins, which may pose additional complications in distinguishing a specific signaling role for cAMP. Here, we have developed rapeseed (Brassica napus L.) transgenic plants that overexpress an inducible plant-origin AC activity for generating high AC levels much like that in animal cells, which served the genetic model disturbing native cAMP signaling as a whole in plants. We found that overexpression of the soluble AC activity had significant impacts on the contents of indole-3-acetic acid (IAA) and stress phytohormones, i.e. jasmonic acid (JA), abscisic acid (ABA), and salicylic acid (SA) in the transgenic plants. Acute induction of the AC activity caused IAA overaccumulation, and upregulation of TAA1 and CYP83B1 in the IAA biosynthesis pathways, but also simultaneously the hyper-induction of PR4 and KIN2 expression indicating activation of JA and ABA signaling pathways. We observed typical overgrowth phenotypes related to IAA excess in the transgenic plants, including significant increases in plant height, internode length, width of leaf blade, petiole length, root length, and fresh shoot biomass, as well as the precocious seed development, as compared to wild-type plants. In addition, we identified a set of 1465 cAMP-responsive genes (CRGs), which are most significantly enriched in plant hormone signal transduction pathway, and function mainly in relevance to hormonal, abiotic and biotic stress responses, as well as growth and development. Collectively, our results support that cAMP elevation impacts phytohormone homeostasis and signaling, and modulates plant growth and development. We proposed that cAMP signaling may be critical in configuring the coordinated regulation of growth and development in higher plants.
... These hormones are paramount for managing environmental stimuli responses and regulating plant growth and development [2,8,9]. Their synthesis and signal pathways also participate in regulating osmotic adjustment and other processes, heightening drought tolerance in plants [2,9,10]. On the other hand, the intricate signaling transduction pathways that perceive and react to drought conditions often drive changes in gene expression, achieved through transcriptional regulation [11,12]. ...
... Alterations in hormonal content and corresponding signaling networks in plants are triggered by drought stress. These modifications aim to enhance tolerance or stimulate programed cell death within distinct cells, tissues, or organs, promoting survival under unfavorable conditions [10,59]. Certain phytohormones, such as ABA and JA, are crucial for regulating plant responses to water stress [38]. ...
Mediator is a multiprotein complex integral to the transcription machinery, mediated by RNA polymerase II. Some Mediator subunits have been found to have critical functions in plants’ responses to abiotic stresses. However, the role of plant Mediator subunits in drought responses remains largely enigmatic. Here, we identified a Mediator subunit, RhMED15a, in roses (Rosa hybrida). Its expression was greatly and swiftly induced by dehydration treatment in the root. The promoter sequence of RhMED15a contains cis-acting elements that respond to abscisic acid (ABA) and methyl jasmonate (MeJA). In addition, the expression of RhMED15a was significantly up-regulated with ABA treatment and inversely down-regulated with MeJA treatment. Silencing RhMED15a using virus-induced gene silencing (VIGS) in roses significantly reduced drought tolerance in rose plants. This resulted in a significant increase in the malondialdehyde (MDA) level and a decreased survival rate in comparison to TRV controls. Moreover, we found that the expression of five drought-related genes, including dehydration responsive element binding factor 1B (DREB1B), responsive to desiccation stress 29A (RD29A), responsive to desiccation stress 29B (RD29B), early response to dehydration 14 (ERD14), and 9-cis-epoxycarotenoid dioxygenase 1 (NCED1), was considerably suppressed in RhMED15a-silenced plants during drought stress. Taken together, our results present that the Mediator tail module subunit RhMED15a serves as an enhancer of drought tolerance in rose, probably through the modulation of the expression of some drought-related genes.
... The hormonal system plays a key role in both plant development (ontogenesis) and the plant's ability to adapt to environmental stresses [8,73]. The adaptation to stress is closely linked to the balance of endogenous phytohormones [74,75]. When plants experience stress, such as drought, typical responses include alterations in hormonal balance characterized by a temporary increase in stress hormone ABA and a decrease in the levels of IAA and CK [75,76]. ...
... The adaptation to stress is closely linked to the balance of endogenous phytohormones [74,75]. When plants experience stress, such as drought, typical responses include alterations in hormonal balance characterized by a temporary increase in stress hormone ABA and a decrease in the levels of IAA and CK [75,76]. In our study, the analysis of endogenous ABA, IAA, and CK in DT and DS plants under normal conditions revealed that DT plants exhibited higher concentrations of CK and ABA compared to the DS variety, while the levels of IAA were maintained at similar levels in both varieties (Figure 2A-C). ...
A comparative analysis was conducted to evaluate the effects of seed priming with endophytic bacterium Bacillus subtilis 10-4 (BS) on the hormonal system and cell wall tolerance (lipid peroxidation (LPO), electrolyte leakage (EL), and root lignin deposition) of two Triticum aestivum L. (wheat) varieties with contrasting drought sensitivities (Ekada 70—drought-tolerant (DT); Salavat Yulaev—drought-sensitive (DS)) under normal conditions and 12% polyethylene glycol-6000 (PEG)-induced osmotic stress. The results showed that under normal conditions, the growth stimulation in wheat plants by BS was attributed to changes in the hormonal balance, particularly an increase in endogenous indole-3-acetic acid (IAA) accumulation. However, under stress, a significant hormonal imbalance was observed in wheat seedlings, characterized by a pronounced accumulation of abscisic acid (ABA) and a decrease in the levels of IAA and cytokinins (CK). These effects were reflected in the inhibition of plant growth. BS exhibited a protective effect on stressed plants, as evidenced by a significantly lower amplitude of stress-induced changes in the hormonal system: maintaining the content of IAA at a level close to the control, reducing stress-induced ABA accumulation, and preventing CK depletion. These effects were further reflected in the normalization of growth parameters in dehydrated seedlings, as well as a decrease in leaf chlorophyll degradation, LPO, and EL, along with an increase in lignin deposition in the basal part of the roots in both genotypes. Overall, the findings demonstrate that BS, producing phytohormones, specifically IAA and ABA, had a more pronounced protective effect on DT plants, as evidenced by a smaller amplitude of stress-induced hormonal changes, higher leaf chlorophyll content, root lignin deposition, and lower cell membrane damage (LPO) and permeability (EL) compared to DS plants.
... According to the newly discovered data, MT application improves barley water stress tolerance by reprogramming endogenous plant hormone production and antioxidant activity, which enhances membrane stability and photosynthesis. This study unraveled MT's crucial role in water deficiency mitigation, which can thus be applied to water stress management. of endogenous hormones by regulating the biosynthesis or degradation of hormones either directly or indirectly [8,14]. Phytohormones are regarded as important endogenous molecules for regulating physiological and biochemical responses, even though the plant's response to stresses is dependent on a variety of factors [10,11]. ...
... The results of the current experiment showed that whereas SA, MT, and ABA content increased, IAA, GAs, and CKs levels were dramatically decreased as a result of water scarcity. This outcome is consistent with earlier research that revealed that in plants grown under stressful environments, IAA, GAs, and CKs content decreased, while SA, MT, and ABA content increased [6, 10,14,41]. According to previous studies, the upregulation of ABA synthesis genes and signaling transcription factors under abiotic challenges could be the cause of the increased amount of endogenous ABA in plants [41,69]. ...
... Plant hormones modulate plant photosynthetic activity in response to abiotic stress [10,11]. In fact, ABA is the key hormone that controls plant water content by altering stomatal conductance in response to challenging conditions [10,14,55]. Similarly, it has been claimed that ABA serves as the core regulatory route in plants' responses to drought, influencing leaf stomatal closure and activating the antioxidant system to reduce drought stress [72]. ...
The production of crops is severely limited by water scarcity. We still do not fully understand the underlying mechanism of exogenous melatonin (MT)-mediated water stress tolerance in barley. This study is the first of its kind to show how MT can potentially mitigate changes in barley’s physio-biochemical parameters caused by water deficiency. Barley was grown under three irrigation levels (100%, 70%, and 30% of field capacity) and was foliar sprayed with 70 μM MT. The results showed that exogenously applied MT protected the photosynthetic apparatus by improving photosynthetic pigment content, photochemical reactions of photosynthesis, Calvin cycle enzyme activity, gas exchange capacity, chlorophyll fluorescence system, and membrane stability index. Furthermore, the increased levels of salicylic acid, gibberellins, cytokinins, melatonin, and indole-3-acetic acid, as well as a decrease in abscisic acid, indicated that foliar-applied MT greatly improved barley water stress tolerance. Additionally, by increasing the activity of antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase and decreasing hydrogen peroxide content, lipid peroxidation, and electrolyte leakage, MT application lessened water stress-induced oxidative stress. According to the newly discovered data, MT application improves barley water stress tolerance by reprogramming endogenous plant hormone production and antioxidant activity, which enhances membrane stability and photosynthesis. This study unraveled MT’s crucial role in water deficiency mitigation, which can thus be applied to water stress management.
