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Drought stress is one of the main environmental factors that limit plant growth and productivity. In order to endure such stress, which increases every year, plants developed different strategies to withstand drought conditions, including an enzymatic antioxidant defense system with enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX), glutathione peroxidase (GPX), and glutathione-S-transferase (GST), among others, playing key roles. Therefore, efforts to develop new drought-tolerant varieties have become essential for maintaining human populations increasing researchers' interest in tools and/or mechanisms involved in drought tolerance. Thus, this work is aimed at offering a systematic review of the correlation between gene expression and antioxidant enzyme activity in water-stress tolerant plants for fourteen most important food crops worldwide, according to FAO, and Arabidopsis thaliana. This systematic review was performed using the free software StArt and the PICOS strategy. Among the factors that generate drought tolerance is the increased activity/gene expression of antioxidant enzymes. The use of plant regulators stood out as the most critical substance among chemical inputs; however, these do not provide long-term tolerance and therefore, the development of genetically modified organisms would be the most efficient technique for promoting tolerance to long-term water deficit in plants. In this systematic review, data was collected, and forty candidate genes were identified as responsible for water deficit tolerance, which can be used by plant breeding programs to develop genetically engineered products. [ABSTRACT FROM AUTHOR]

Rosa damascena is one of the oldest valuable rose flower varieties that is almost drough tolerant. However, selecting and identifying landraces that are more tolerant to drought conditions will be effective in developing the cultivation of the plant under stress. The most important step in developing drought-tolerant plants is the evaluation and identification of resistant and susceptible genotypes. In this case, an experiment was performed under in vitro conditions using five levels (0, 25, 50, 75, and 100 g/L) of polyethylene glycol (PEG) on four landraces of the Damask rose (Maragheh, Urmia, Pakdasht, and Kashan). Based on the findings, the resistance of the different landraces to a water deficit was measured by the Design-Expert software using the response level (RSM) method. The results showed that Maragheh, with the highest fresh and dry weight, total chlorophyll, chlorophyll a, chlorophyll b, proline and an increase in the superoxide dismutase activity, had a high tolerance to drought stress. Moreover, Maragheh with a decreasing leaf number, height, malondialdehyde, hydrogen peroxide and having a higher membrane stability index, showed a better defence mechanism against oxidative stress than the other landraces. Also, after Maragheh, Pakdasht had the best performance compared to the other two landraces up to 75g/L of PEG, but not as well as Maragheh at the highest level of the tested PEG. Urmia and especially Kashan probably do not have much tolerance to drought stress regarding all the results and levels of desirability.

Climate change alters regular weather seasonality. Corn is one of the main crops affected by irregular water regimes. Due to complications in decision-making processes related to climate change, it is estimated that planting corn outside the optimal window results in around USD 340 million in losses per year in the United States' Corn Belt. In turn, exogenous plant growth regulators have been gaining prominence due to their potential to positively influence the morphology and physiology of plants under stress. This study was based on the hypothesis that the use of plant growth regulators can assist in mitigating the adverse effects of climate change on corn plants sown both inside and outside the recommended planting period. In this context, the effects of biostimulant application on gas exchange in corn plants sown within and outside the recommended period were evaluated. The experiment was carried out in randomized blocks in a 4 × 5 × 2 factorial scheme with four repetitions. These were four sowing times, the application of the biostimulants via seeds in five doses, and foliar applications (presence and absence). The biostimulant doses were 0.00, 6.25, 12.50, 18.75, and 25 mL kg−1. The foliar application used a dose of 500 mL ha−1. Only in the period (2017/2) higher doses of biostimulants indicated a decrease in the water use efficiency of plants, suggesting the need to evaluate this variable carefully. In this regard, future studies may investigate the ideal doses and application timings of biostimulants for different edaphoclimatic conditions. In general, the combined use of biostimulants on seeds and as a foliar treatment boosted physiological activity and stimulated photosynthetic processes in corn plants. Based on these data, plant regulators can be a useful tool to mitigate the adverse effects of climate change on corn plants sown inside and outside the planting period. [ABSTRACT FROM AUTHOR]

Water deficit during grain filling is a key factor on soybean (Glycine max (L.) Merrill) production, but plant response to different water stress levels should be better understood. This study evaluated soybean plant response to different soil water levels during grain filling. It was assessed the gravimetrical humidity and soil matric potential, leaf relative water content, leaf water potential, proline, and yield components of plants under a range of days without irrigation (0, 3, 6, 9, and 12) during grain filling phase. Until soil matric potential was around −0.8 atm soybean water deficit tolerance mechanisms were enough to maintain leaf relative water content and leaf water potential at acceptable levels, which proline concentration was a key factor in this mechanism. Leaf relative water content and leaf water potential showed to be related in maintaining soybean yield under water deficit and they may be used in studies of soybean tolerant cultivars to water restriction. From 9 days on, critical yield losses were observed due to water stress. The information presented in this study supports soybean producers in decision-making in irrigated systems to minimize productivity losses due to water deficit during the critical period of the crop–grain filling. [ABSTRACT FROM AUTHOR]

Rosa damascena is one of the oldest valuable rose flower varieties that is almost drough tolerant. However, selecting and identifying landraces that are more tolerant to drought conditions will be effective in developing the cultivation of the plant under stress. The most important step in developing drought-tolerant plants is the evaluation and identification of resistant and susceptible genotypes. In this case, an experiment was performed under in vitro conditions using five levels (0, 25, 50, 75, and 100 g/L) of polyethylene glycol (PEG) on four landraces of the Damask rose (Maragheh, Urmia, Pakdasht, and Kashan). Based on the findings, the resistance of the different landraces to a water deficit was measured by the Design-Expert software using the response level (RSM) method. The results showed that Maragheh, with the highest fresh and dry weight, total chlorophyll, chlorophyll a, chlorophyll b, proline and an increase in the superoxide dismutase activity, had a high tolerance to drought stress. Moreover, Maragheh with a decreasing leaf number, height, malondialdehyde, hydrogen peroxide and having a higher membrane stability index, showed a better defence mechanism against oxidative stress than the other landraces. Also, after Maragheh, Pakdasht had the best performance compared to the other two landraces up to 75g/L of PEG, but not as well as Maragheh at the highest level of the tested PEG. Urmia and especially Kashan probably do not have much tolerance to drought stress regarding all the results and levels of desirability. [ABSTRACT FROM AUTHOR]

Water deficit negatively impacts crop productivity and quality. Plants face these challenges by adjusting biological processes and molecular functions according to the intensity and duration of the stress. The cultivated potato (Solanum tuberosum) is considered sensitive to water deficit, thus breeding efforts are needed to enhance its resilience. To capture novel functional information and gene regulatory networks, we carried out mass spectrometry-based proteomics in potato cell suspensions exposed to abrupt or stepwise osmotic stresses. Both forms of stress triggered significant alterations in protein expression, though with divergent response mechanisms. Stress response pathways orchestrated by key proteins enrolled in primary and secondary metabolism, antioxidant processes, transcriptional and translational machinery and chromatin organization were found in adapted cells. Target metabolites and reactive oxygen species levels were quantified to associate functional outcomes with the proteome study. Remarkably, we also showed that adapted cells tolerate an array of diverse conditions, including anoxia, salt and heat stress. Finally, the expression patterns of genes encoding selected differentially expressed proteins were investigated in potato plants subjected to either drought or salt stress. Collectively, our findings reveal the complex cellular strategies of osmotic stress adaptation, identifying new fundamental genes that could enhance potato resilience., (© 2024 The Author(s). Plant, Cell & Environment published by John Wiley & Sons Ltd.)

Climate change alters regular weather seasonality. Corn is one of the main crops affected by irregular water regimes. Due to complications in decision-making processes related to climate change, it is estimated that planting corn outside the optimal window results in around USD 340 million in losses per year in the United States’ Corn Belt. In turn, exogenous plant growth regulators have been gaining prominence due to their potential to positively influence the morphology and physiology of plants under stress. This study was based on the hypothesis that the use of plant growth regulators can assist in mitigating the adverse effects of climate change on corn plants sown both inside and outside the recommended planting period. In this context, the effects of biostimulant application on gas exchange in corn plants sown within and outside the recommended period were evaluated. The experiment was carried out in randomized blocks in a 4 × 5 × 2 factorial scheme with four repetitions. These were four sowing times, the application of the biostimulants via seeds in five doses, and foliar applications (presence and absence). The biostimulant doses were 0.00, 6.25, 12.50, 18.75, and 25 mL kg−1. The foliar application used a dose of 500 mL ha−1. Only in the period (2017/2) higher doses of biostimulants indicated a decrease in the water use efficiency of plants, suggesting the need to evaluate this variable carefully. In this regard, future studies may investigate the ideal doses and application timings of biostimulants for different edaphoclimatic conditions. In general, the combined use of biostimulants on seeds and as a foliar treatment boosted physiological activity and stimulated photosynthetic processes in corn plants. Based on these data, plant regulators can be a useful tool to mitigate the adverse effects of climate change on corn plants sown inside and outside the planting period.

Drought stress is a serious limiting factor to rice production, which results in huge economic losses. It is becoming a more serious issue with respect to the global climate change. Keeping in view of the current and forecasted global food demand, it has become essential to enhance the crop productivity on the drought-prone rainfed lands with priority. In order to achieve the production target from rainfed areas, there is a requirement of rice varieties with drought tolerance, and genetic improvement for drought tolerant should be a high priority theme of research in the future. Breeding for drought tolerant rice varieties is a thought-provoking task because of the complex nature and multigenic control of drought tolerant traits would be a major bottleneck for the current research. A great progress has been made during last two decades in our understanding of the mechanisms involved in adaptation and tolerance to drought stress in rice. In this review, we highlighted the recent progresses in physiological, biochemical and molecular adaptation of rice to drought tolerance. A brief discussion on the molecular genetics and breeding approaches for drought tolerance in rice will be focused for the future crop improvement program for development of drought tolerant rice varieties.

Limited soil water availability is a major threat to agricultural productivity because it inhibits plant growth and yields. Soil microorganisms having the ability to alleviate abiotic stress and promoting plant development would be highly valuable tools in sustainable agriculture. To this purpose, two Rhizobium leguminosarum strains were tested for their potential to induce tolerance against water deficits in Triticum durum grown under two hydric conditions in greenhouse experiments. For this, physiological and biochemical parameters were measured as criteria to assess the effect of R. leguminosarum inoculation on T. durum under water deficiency. In the presence of rhizobia, wheat plants were able to withstand water stress more effectively than un-inoculated plant, as indicated by the recorded increases in relative water content of inoculated plants compared to un-inoculated plants, higher accumulation of osmoprotectant (soluble sugar), lower MDA and H2O2 accumulation, and increased in antioxidant responses (peroxidase). Under water-limited condition, co-inoculation of selected rhizobia was better than single application for one of studied genotype, which let us hypothesize that this variation in responsiveness indicates a possible genotype effect. As a result, rhizobia from various legumes have a huge potential for enhancing the water deficiency stress tolerance of cereals. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of water deficit on the physiological response and yield of three Andean potato cultivars. Leaf water potential (Ψw), soil matric potential (SMP), photosynthesis (A), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUEi), leaf temperature (LT), chlorophyll fluorescence parameters, chlorophyll (Chl), carotenoids (Car), electrolyte leakage (EL), growth and yield (Y). Parameters were determined in well-watered (WW) and drought-stressed (DS) plants. The three DS cultivars showed a decrease in leaf Ψw from the first day of treatment and reached values close to -2.00 MPa 4 days after treatment (DAT) for the Diacol Capiro (DC) cultivar, 5 DAT for the Pastusa Suprema (PS) cultivar and 6 DAT for the Esmeralda (Es) cultivar. The values of A, gs and E in the DS cultivars decreased from the first DAT. The LT reached the highest values when gs showed the lowest values for the three DS cultivars. WUEi was higher in Es under DS plants but lower in DC under DS. The PSII photochemical efficiency (Fv/Fm) showed values greater than 0.8 for all DS cultivars under DS, suggesting the absence of non-stomatal limitations for A. The Chl content increased in the Es cultivar under DS from 5 to 7 DAT compared to WW plants. Carotenoids (Ca) contents, the Car/Chl ratio, and EL increased in the three DS cultivars. There were no differences in yield and growth parameters between WW and DS cultivars. These results suggest that the three cultivars developed mechanisms to overcome the stress. One of these mechanisms could be the early synthesis of Car, which may maintain photosystem II function under water stress.

Water deficits are the major constraint in some potato-growing areas of the world. The effect is most severe at the tuberization stage, resulting in lower yield. Therefore, an assessment of genetic and phenotypic variations resulting from water deficits in Colombia germplasm is required to accelerate breeding efforts. Phenotypic variations in response to a water deficit were studied in a collection of Solanum tuberosum Group Phureja. A progressive water deficit experiment on the tuberization stage was undertaken using 104 genotypes belonging to the Working Collection of the Potato Breeding Program at the Universidad Nacional de Colombia. The response to water deficit conditions was assessed with the relative chlorophyll content (CC), maximum quantum efficiency of PSII (Fv/Fm), relative water content (RWC), leaf sugar content, tuber number per plant (TN) and tuber fresh weight per plant (TW). Principal Component Analysis (PCA) and cluster analysis were used, and the Drought Tolerance Index (DTI) was calculated for the variables and genotypes. The soluble sugar contents increased significantly under the deficit conditions in the leaves, with a weak correlation with yield under both water treatments. The PCA results revealed that the physiological, biochemical and yield-component variables had broad variation, while the yield-component variables more powerfully distinguished between the tolerant and susceptible genotypes than the physiological and biochemical variables. The PCA and cluster analysis based on the DTI revealed different levels of water deficit tolerance for the 104 genotypes. These results provide a foundation for future research directed at understanding the molecular mechanisms underlying potato tolerance to water deficits.

In plant cells, vacuolar H+-ATPases (V-ATPases) are responsible for deacidification of the cytosol and energisation of the secondary transport processes across the tonoplast. A number of V-ATPase subunit genes have been demonstrated to be involved in the regulation of the plant response to water deficit. However, there are no reports on the role of V-ATPase subunit A (VHA-A) in dehydration tolerance of cotton. In this study, cotton GhVHA-A gene was functionally characterized, especially with regard to its role in dehydration stress tolerance. Expression analysis showed that GhVHA-A was differentially expressed in various cotton organs and was induced by dehydration, low temperature, high salinity, and abscisic acid treatment in leaves. We also report that GhVHA-A improve dehydration tolerance in transgenic tobacco and cotton. Virus-induced gene silencing of GhVHA-A decreased the tolerance of cotton plantlets to dehydration stress. Silencing GhVHA-A decreased chlorophyll content and antioxidant enzyme activities and increased malondialdehyde (MDA) content in cotton under dehydration stress. However, transgenic tobacco expressing GhVHA-A exhibited enhanced dehydration resistance, resulting in reduced leaf water loss, higher average root length, and lower MDA levels under dehydration stress. Meanwhile, overexpression of GhVHA-A in tobacco conferred water deficit tolerance by enhancing osmotic adjustment (proline) and the activities of the antioxidant enzymes superoxide dismutase and peroxidase, thereby enhancing reactive oxygen species detoxification. These results suggest that GhVHA-A plays an important role in conferring resistance to dehydration stress. Our results have identified GhVHA-A as a candidate gene for improving dehydration tolerance in plants.

In plant cells, vacuolar HC+ATPases (V-ATPases) are responsible for deacidification of the cytosol and energisation of the secondary transport processes across the tonoplast. A number of V-ATPase subunit genes have been demonstrated to be involved in the regulation of the plant response to water deficit. However, there are no reports on the role of V-ATPase subunit A (VHA-A) in dehydration tolerance of cotton. In this study, cotton GhVHA-A gene was functionally characterized, especially with regard to its role in dehydration stress tolerance. Expression analysis showed that GhVHA-A was differentially expressed in various cotton organs and was induced by dehydration, low temperature, high salinity, and abscisic acid treatment in leaves. We also report that GhVHA-A improve dehydration tolerance in transgenic tobacco and cotton. Virus-induced gene silencing of GhVHA-A decreased the tolerance of cotton plantlets to dehydration stress. Silencing GhVHA-A decreased chlorophyll content and antioxidant enzyme activities and increased malondialdehyde (MDA) content in cotton under dehydration stress. However, transgenic tobacco expressing GhVHAA exhibited enhanced dehydration resistance, resulting in reduced leaf water loss, higher average root length, and lower MDA levels under dehydration stress. Meanwhile, overexpression of GhVHA-A in tobacco conferred water deficit tolerance by enhancing osmotic adjustment (proline) and the activities of the antioxidant enzymes superoxide dismutase and peroxidase, thereby enhancing reactive oxygen species detoxification. These results suggest that GhVHA-A plays an important role in conferring resistance to dehydration stress. Our results have identified GhVHA-A as a candidate gene for improving dehydration tolerance in plants. [ABSTRACT FROM AUTHOR]

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Drought is one of the most important environmental stresses in agriculture. It significantly reduces both the quality and yield of agricultural crops. Under conditions in Poland, spring barley is more sensitive to drought than winter barley. In plants, the expression of dehydrins increases the ability to absorb and hold water in the cell. One can try to obtain plants with increased resistance to drought, among other things, through the selection of genotypes with increased accumulation of dehydrins. The aim of our study was to examine differences in the expression levels of SRG6 and HVA1 genes in Polish breeding lines of spring barley. In this experiment measurements of the accumulation levels of HVA1 and SRG6 transcripts by means of real-time PCR were performed in twenty seven barley genotypes. Estimations of mRNA abundance were made before drought and on the 15th day of the experiment at a relative maximum water capacity of 32%. The results of our experiments showed that drought stress caused a significant increase in the expression of HVA1 and SRG6 genes in all genotypes. The 27 studied breeding strains of spring barley from Polish breeding companies were characterized by high variation in the expression of both genes. [ABSTRACT FROM AUTHOR]

Plant cysteine protease (CP) genes are induced by abiotic stresses such as drought, yet their functions remain largely unknown. We isolated the full-length cDNA encoding a Triticum aestivum CP gene, designated TaCP, from wheat by the rapid amplification of cDNA ends (RACE) method. Sequence analysis revealed that TaCP contains an open reading frame encoding a protein of 362 amino acids, which is 96% identical to barley cysteine protease HvSF42. The TaCP transcript level in wheat seedlings was upregulated during polyethylene glycol (PEG) stress, with a peak appearing around 12 h after treatment. TaCP expression level increased rapidly with NaCl treatment at 48 h. TaCP responded strongly to low temperature (4°C) treatment from 1 h post-treatment and reached a peak of about 40-fold at 72 h. However, it showed only a very slight response to abscisic acid (ABA). More than one copy of TaCP was present in each of the three genomes of hexaploid wheat and its diploid donors. TaCP fused with green fluorescent protein (GFP) was located in the plasma membrane of onion epidermis cells. Transgenic Arabidopsis plants overexpressing TaCP showed stronger drought tolerance and higher CP activity under water-stressed conditions than wild-type Arabidopsis plants. The results suggest that TaCP plays a role in tolerance to water deficit. [ABSTRACT FROM AUTHOR]

Six Populus deltoides Bartr. ex Marsh. × P. nigra L. genotypes were selected to investigate whether stem xylem anatomy correlated with gas exchange rates, water-use efficiency (WUE) and growth performance. Clonal copies of the genotypes were grown in a two-plot common garden test under contrasting water regimes, with one plot maintained irrigated and the other one subjected to moderate summer water deficit. The six genotypes displayed a large range of xylem anatomy, mean vessel and fibre diameter varying from about 40 to 60 μm and from 7.5 to 10.5 μm, respectively. Decreased water availability resulted in a reduced cell size and an important rise in vessel density, but the extent of xylem plasticity was both genotype and trait dependent. Vessel diameter and theoretical xylem-specific hydraulic conductivity correlated positively with stomatal conductance, carbon isotope discrimination and growth performance-related traits and negatively with intrinsic WUE, especially under water deficit conditions. Vessel diameter and vessel density measured under water deficit conditions correlated with the relative losses in biomass production in response to water deprivation; this resulted from the fact that a more plastic xylem structure was generally accompanied by a larger loss in biomass production. [ABSTRACT FROM PUBLISHER]

Water deficits are the major constraint in some potato-growing areas of the world. The effect is most severe at the tuberization stage, resulting in lower yield. Therefore, an assessment of genetic and phenotypic variations resulting from water deficits in Colombia germplasm is required to accelerate breeding efforts. Phenotypic variations in response to a water deficit were studied in a collection of Solanum tuberosum Group Phureja. A progressive water deficit experiment on the tuberization stage was undertaken using 104 genotypes belonging to the Working Collection of the Potato Breeding Program at the Universidad Nacional de Colombia. The response to water deficit conditions was assessed with the relative chlorophyll content (CC), maximum quantum efficiency of PSII (Fv/Fm), relative water content (RWC), leaf sugar content, tuber number per plant (TN) and tuber fresh weight per plant (TW). Principal Component Analysis (PCA) and cluster analysis were used, and the Drought Tolerance Index (DTI) was calculated for the variables and genotypes. The soluble sugar contents increased significantly under the deficit conditions in the leaves, with a weak correlation with yield under both water treatments. The PCA results revealed that the physiological, biochemical and yield-component variables had broad variation, while the yield-component variables more powerfully distinguished between the tolerant and susceptible genotypes than the physiological and biochemical variables. The PCA and cluster analysis based on the DTI revealed different levels of water deficit tolerance for the 104 genotypes. These results provide a foundation for future research directed at understanding the molecular mechanisms underlying potato tolerance to water deficits. [ABSTRACT FROM AUTHOR]

In plant cells, vacuolar H + -ATPases (V-ATPases) are responsible for deacidification of the cytosol and energisation of the secondary transport processes across the tonoplast. A number of V-ATPase subunit genes have been demonstrated to be involved in the regulation of the plant response to water deficit. However, there are no reports on the role of V-ATPase subunit A (VHA-A) in dehydration tolerance of cotton. In this study, cotton GhVHA-A gene was functionally characterized, especially with regard to its role in dehydration stress tolerance. Expression analysis showed that GhVHA-A was differentially expressed in various cotton organs and was induced by dehydration, low temperature, high salinity, and abscisic acid treatment in leaves. We also report that GhVHA-A improve dehydration tolerance in transgenic tobacco and cotton. Virus-induced gene silencing of GhVHA-A decreased the tolerance of cotton plantlets to dehydration stress. Silencing GhVHA-A decreased chlorophyll content and antioxidant enzyme activities and increased malondialdehyde (MDA) content in cotton under dehydration stress. However, transgenic tobacco expressing GhVHA-A exhibited enhanced dehydration resistance, resulting in reduced leaf water loss, higher average root length, and lower MDA levels under dehydration stress. Meanwhile, overexpression of GhVHA-A in tobacco conferred water deficit tolerance by enhancing osmotic adjustment (proline) and the activities of the antioxidant enzymes superoxide dismutase and peroxidase, thereby enhancing reactive oxygen species detoxification. These results suggest that GhVHA-A plays an important role in conferring resistance to dehydration stress. Our results have identified GhVHA-A as a candidate gene for improving dehydration tolerance in plants.