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Leptochloa chinensis is a troublesome rice weed in many countries, and knowledge of its seed germination ecology varied in different reports. To reveal the range and general characteristics of L. chinensis seed germination under different drought stresses, and seedling emergence under different burial depths, we conducted a serial of germination experiments with 242 L. chinensis populations collected along ranges spanning 4° latitudes and 4° longitudes from rice fields in eastern China. We found that 1000‐seed weight ranged from 0.056 to 0.129 g, with an average of 0.088 g; the OR50 (the osmotic potentials at which the germination percentage reaches 50%) was −0.47 to −0.07 MPa, with an average of −0.28 MPa; and BR50 (the burial depth at which the emergence percentage reaches 50%) ranged from 0.07 to 0.26 cm, with an average of 0.18 cm. At −0.5 MPa, the mean germination percentage of 242 populations was 4.1%. Seed germination percentages under 0.5 and 1.5 cm quartz sand layer were both >75%, while no seedling emerged up to the surface of quartz sand. Populations collected from rice fields in northern regions leaned to be higher in 1000‐seed weights, and OR50 values. Moreover, populations collected from transplanting rice fields slightly and significantly leaned to be more adapted to drought stresses and soil burial depths. The ability to quickly germinate, together with seed germination sensitive to drought stress and seedling emergence sensitive to soil burial, facilitate L. chinensis to avoid suicide seed germination, occupy niches under suitable environments and escape chemical control practices on rice fields. [ABSTRACT FROM AUTHOR]

Background: Accumulation of coumarins plays key roles in response to immune and abiotic stress in plants, but the genetic adaptation basis of controlling coumarins in perennial woody plants remain unclear. Results: We detected 792 SNPs within 334 genes that were significantly associated with the phenotypic variations of 15 single-metabolic traits and multiple comprehensive index, such as principal components (PCs) of coumarins metabolites. Expression quantitative trait locus mapping uncovered that 337 eQTLs associated with the expression levels of 132 associated genes. Selective sweep revealed 55 candidate genes have potential selective signature among three geographical populations, highlighting that the coumarins biosynthesis have been encountered forceful local adaptation. Furthermore, we constructed a genetic network of seven candidate genes that coordinately regulate coumarins biosynthesis, revealing the multiple regulatory patterns affecting coumarins accumulation in Populus tomentosa. Validation of candidate gene variations in a drought-tolerated population and DUF538 heterologous transformation experiments verified the function of candidate genes and their roles in adapting to the different geographical conditions in poplar. Conclusions: Our study uncovered the genetic regulation of the coumarins metabolic biosynthesis of Populus, and offered potential clues for drought-tolerance evaluation and regional improvement in woody plants. [ABSTRACT FROM AUTHOR]

Drought is considered one of the most critical abiotic environmental stresses and limits plant growth, development, and productivity. It constitutes a real threat to humanity, especially in dry areas worldwide. Plants manage the negative effects of drought through a complex set of related mechanisms. Knowledge of plant responses and adaptation is more meaningful in plant breeding and genetics for improving drought resistance species. This review will focus on drought response mechanisms and drought adaptation, providing examples from plant species differing in their life-form, including herbaceous and woody plants. Additionally, the potential role of enhancing plant drought responses will be emphasized. This review is of potential significance to researchers and those who wish to obtain a glimpse into plant behavior under drought conditions. [ABSTRACT FROM AUTHOR]

The cytoplasm of most plant cells is connected by membrane-lined cell wall channels, the plasmodesmata (PD). Dynamic regulation of sugar, hormone, and protein diffusion through PD is essential for plant development and stress responses. Understanding this regulation requires knowledge of factors and mechanisms that control PD permeability through the modulation of callose levels in the cell wall around PD openings. We investigated PD regulation in leaf epidermal cells in relation to drought stress in Arabidopsis. PD-mediated cell wall permeability was decreased by drought stress and the hormone abscisic acid (ABA), and we tested how this related to several PD-associated genes with drought-responsive expression. Mutants of NON-RACE SPECIFIC DISEASE RESISTANCE/HIN1 HAIRPIN-INDUCED-LIKE 12 (NHL12) showed relatively low PD permeability that was unaffected by drought or ABA treatment. Overexpression of NHL12 in Nicotiana benthamiana epidermal cells increased PD permeability. Moreover, we showed that NHL12 can potentially interact with the callose synthase regulator NHL3 and we explored the effect of NHL12 abundance and/or lower interface permeability on ABA signaling genes. Our results indicate that NHL12 is a drought-responsive negative regulator of PD callose levels and, thereby, interface permeability. Results are discussed in relation to PD function during drought stress and the regulation of intercellular transport. [ABSTRACT FROM AUTHOR]

While humic substances (HS) are recognized for their role in enhancing plant growth under abiotic stress by modulating hormonal and redox metabolisms, a key question remains: how do HS influence the microbiota associated with plants? This study hypothesizes that the effects of HS extend beyond plant physiology, impacting the plant-associated bacterial community. To explore this, we investigated the combined and individual impacts of HS and osmotic stress on tomato plant physiology and root endophytic communities. Tomatoes were grown within a sterile hydroponic system, which allowed the experiment to focus on seed-transmitted endophytic bacteria. Moreover, sequencing the 16S-ITS-23S region of the rrn operon (~4,500 bp) in a metabarcoding assay using the PNA-chr11 clamp nearly eliminated the reads assigned to Solanum lycopersicum and allowed the species-level identification of these communities. Our findings revealed that HS, osmotic stress, and their combined application induce changes in bacterial endophytic communities. Osmotic stress led to reduced plant growth and a decrease in Bradyrhizobium sp., while the application of HS under osmotic stress resulted in increased tomato growth, accompanied by an increase in Frigoribacterium sp., Roseateles sp., and Hymenobacter sp., along with a decrease in Sphingomonas sp. Finally, HS application under non-stress conditions did not affect plant growth but did alter the endophytic community, increasing Hymenobacter sp. and decreasing Sphingomonas sp. This study enhances the understanding of plant–endophyte interactions under stress and HS application, highlighting the significance of the vertically transmitted core microbiome in tomato roots and suggesting new insights into the mode of action of HS that was used as a biostimulant. [ABSTRACT FROM AUTHOR]

This study performed a bioinformatics analysis of the CsNAC30 gene and examined its expression levels in cucumber leaves and roots under drought stress induced by PEG-6000. The bioinformatics analysis showed that the open reading frame (ORF) of CsNAC30 is 1254 bp, encoding a protein consisting of 417 amino acids. This protein is relatively unstable and hydrophilic, lacks transmembrane regions, and contains 49 phosphorylation sites. It also features a conserved NAM domain at the N-terminus. Homology and phylogenetic analyses indicate that CsNAC30 is a member of the NAC transcription factor family and is most closely related to the melon CMeNAC105 and the winter melon BhNAC96. Quantitative real-time PCR (qPCR) revealed that CsNAC30 expression is induced by drought stress, with relative levels increasing in both leaves and roots following PEG treatment. Expression peaked at 6 h in leaves and 9 h in roots before decreasing. These findings suggest that CsNAC30 plays a role in the cucumber's response to drought stress. [ABSTRACT FROM AUTHOR]

Drought is a serious problem that impacts sugarcane production and productivity worldwide. In this current investigation, a codon-optimized choline oxidase (codA) gene was transformed into Saccharum hybrid cultivar Co 86032 through Agrobacterium-mediated transformation. The transgenic events with the codA gene driven by the portubi882 (PD2) promoter accumulated elevated levels of glycine betaine (5 – 10µg/g) whereas untransformed control plants accumulated less than 1.5µg/g which in turn maintained the plant health by sustaining transpiration rate (4 – 5 µmol of H2O/cm2/s) and photosynthetic efficiency (30 – 34 µmol/Co2/s) whereas the control plants suffered from 50% reduction under water-deficit stress condition. Morpho-anatomic cross-sections of both transgenic events and control plants exhibited significant differences in the epidermal layer and sclerenchyma cells under stress conditions. The relative water content (71 – 76%) and chlorophyll fluorescence (0.60 – 0.72 Fv/Fm) were higher in transgenic events compared to control plants respectively recorded 59% and 0.50 respectively. In addition, significantly elevated activity of antioxidant enzymes viz., superoxide dismutase (95 – 102 U/g), catalase (65 – 73 umol/min/g), ascorbate peroxidase (1700 – 1900 umol/min/mg) and glutathione reductase (17 – 20 umol/min/mg) were observed in transgenic events along with reduced levels of hydrogen peroxide (14 – 16 µmol/g) and malondialdehyde (14 – 17 nmol/g) content. Transgenic events recorded significantly higher arial biomass content compared to untransformed plant after the drought stress. Overall, the increased expression levels of codA gene in sugarcane events resulted in an enhanced ability to withstand water-deficit conditions. [ABSTRACT FROM AUTHOR]

Plant growth regulators (PGRs) improve crop growth and mitigate the adverse effects of drought stress. This study explores the effects of various PGRs including melatonin (MT), indole‐butyric acid (IBA) and gibberellic acid (GA3) on drought‐tolerant Zhongzhe 9 (ZZ9) and Xintaitang 22 (ROC22), as well as drought‐sensitive varieties Guitang‐44 (GT44) and Funong 41 (FN41) varieties. A pot experiment was conducted to evaluate the foliar application of these hormones alone or in combination on sugarcane seedlings under drought stress conditions. At the sixth leaf stage, drought stress was induced by reducing soil moisture to 40%–45% field capacity. Results showed that the drought‐sensitive variety GT44 had the highest plant height (17.97 cm), while PGRs application enhanced the relative water content (RWC) in FN41 by 0.96%. PGRs treatment also increased plant height by 33.98% and RWC by 3.26% compared to controls. MT application significantly increased chlorophyll a and b contents in FN41 by 4.82% and 4.51%, respectively. Antioxidant enzyme activities superoxide dismutase and peroxidase increased by 16.39% and 12.57%, respectively, indicating enhanced oxidative stress defence. Moreover, PGRs applications reduced hydrogen peroxide and malondialdehyde (MDA) accumulation, signifying decreased oxidative damages. The combinations of MT + GA3 and MT + IBA + GA3 significantly improved the plant growth attributes, antioxidant enzymes, osmolytes and reduced the accumulation of ROS and MDA content in both tolerant and sensitive varieties under drought stress. Thus, combined application of MT + GA3 and MT + IBA + GA3 treatments effectively mitigated drought stress in sugarcane seedlings, providing valuable insights for sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Despite the importance of phosphate and iron in plant nutrition, their combined effects on sugar beet's physiological and biochemical responses to drought stress remain unexplored. This study aims to fill this gap and optimize nutrient management for enhanced drought tolerance. A split-plot design with three irrigation regimes (optimal, mild, and severe stress) as main plots and 6 combinations of two iron (F0 and F5 are 0 and 5 kg/ha, respectively) and three phosphorus (P0, P75, and P150 are 0, 75, and 150 kg/ha, respectively) fertilizers as subplots. Medium (P75) and high (P150) phosphate doses, particularly with iron (Fe5), enhanced antioxidant enzymes, catalase and superoxide dismutase, by up to 72%, photosynthetic efficiency (chlorophyll content, Fv/Fm, photosynthetic rate) by up to 107%, and osmolyte accumulation (proline and soluble sugars) by up to 73%. These treatments improved water relations, increasing relative water content by up to 56%, reducing vapor pressure deficit by up to 57%, and making osmotic potential (ψs) up to 57% less negative. However, oxidative stress (malondialdehyde) increased by up to 200%. Despite this, the improved physiological and biochemical functions enhanced white sugar yield by up to 59% and root yield by up to 56%, highlighting the effectiveness of these treatments in increasing sugar beet productivity under drought stress. In conclusion, medium and high phosphate doses, especially when combined with iron, improved drought tolerance and yield in sugar beet under stress by enhancing antioxidant activities, photosynthetic efficiency, osmolyte accumulation, and water relations while reducing oxidative stress and water loss. [ABSTRACT FROM AUTHOR]

Members of the NAC (NAM, ATAF1/2, CUC1/2) transcription factor (TFs) family play a crucial role in Brassica oleracea var. acephala growth regulation, developmental processes, and responses to abiotic stress. However, few studies have examined the roles of NAC proteins in the drought resistance of kale. Here, the NAC TF BoNAC02 was identified. It was strongly induced by drought and abscisic acid (ABA) and localized to the nucleus; it also transcriptionally activates the expression of other genes. The RNAi-induced silencing of BoNAC02 significantly weakened the drought stress tolerance of plants, and overexpression of BoNAC02 enhanced plant drought tolerance. Specifically, ABA mediated the regulation of drought tolerance via BoNAC02. In the expression analysis of drought resistance-related genes, significant changes were observed in the expression of genes related to ABA signaling and oxidase metabolism in BoNAC02-silenced plants. This result strongly suggested that BoNAC02 positively regulates ABA signaling and the drought response. Our findings provide new insights into the role of TFs, especially BoNAC02, in the stress resistance of plants; our results also have implications for the approaches to enhance the drought resistance of kale plants. [ABSTRACT FROM AUTHOR]

This study employed genome‐wide association studies (GWAS) to identify the crucial marker–trait associations (MTAs) for agronomic and physiological traits in bread wheat grown under full irrigation and 40% reduced irrigation. One hundred twenty‐four genotypes derived from three‐way crosses of landraces and synthetic bread wheat were evaluated for 2 years in the field conditions of CIMMYT Obregon, Mexico. Irrigation was not provided at anthesis and post‐anthesis stage for the drought treatment, and data of 12 traits were recorded. Most of the traits were reduced significantly under drought conditions except for vigour, wax and spike length (SL); genotypes were significantly different for the eight traits except for days to heading (DTH), number of grains spike−1 (NGS), normalized difference in vegetation index (NDVI) and canopy temperature depression (CTD); and differences were also significant for five traits between the years. Moreover, GY was significantly and negatively correlated with wax and CTD. Our GWAS results indicated 117 significant (p ≤ 0.001) MTAs distributed on all the wheat chromosomes except chromosomes 4B and 4D explaining 10%–21.5% of the phenotypic variation of the corresponding traits. Moreover, 22 MTAs were recorded for grain yield and explaining the phenotypic variations up to 14.7% with one common association under both irrigated and drought conditions. Additionally, we also identified the associations for NDVI, CTD and SL at chromosome 1B, suggesting that genotypes are sustaining superior grain yield through better values of traits like NDVI, CTD, and SL under the challenging conditions of anthesis and post‐anthesis drought stress. [ABSTRACT FROM AUTHOR]

Summary: It is well‐known that the mycorrhizal type of plants correlates with different modes of nutrient cycling and availability. However, the differences in drought tolerance between arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) plants remains poorly characterized.We synthesized a global dataset of four hydraulic traits associated with drought tolerance of 1457 woody species (1139 AM and 318 EcM species) at 308 field sites. We compared these traits between AM and EcM species, with evolutionary history (i.e. angiosperms vs gymnosperms), water availability (i.e. aridity index) and biomes considered as additional factors.Overall, we found that evolutionary history and biogeography influenced differences in hydraulic traits between mycorrhizal types. Specifically, we found that (1) AM angiosperms are less drought‐tolerant than EcM angiosperms in wet regions or biomes, but AM gymnosperms are more drought‐tolerant than EcM gymnosperms in dry regions or biomes, and (2) in both angiosperms and gymnosperms, variation in hydraulic traits as well as their sensitivity to water availability were higher in AM species than in EcM species.Our results suggest that global shifts in water availability (especially drought) may alter the biogeographic distribution and abundance of AM and EcM plants, with consequences for ecosystem element cycling and ultimately, the land carbon sink. [ABSTRACT FROM AUTHOR]

In the 2018/19 growing season, a multi-environment trial in Opiki, Hastings, and Ohakune located in three different regions of the North Island of New Zealand was conducted to evaluate responses of selected potato cultivars to abiotic stress associated with climate change. Heat and drought stresses were evident with supra-optimal temperatures (> 25 °C) in Opiki and Hastings and sub-optimal rainfall (< 500 mm) in Opiki, which influenced the different morpho-physiological characteristics of the potato crop, ultimately affecting yield and tuber quality. These abiotic stresses also increased the incidence of malformation, growth cracks, and second growth in tubers reducing the total and marketable tuber yields by 43% and 45%, respectively. In addition, the genotype × environment analysis showed that Ohakune had the most favourable environmental conditions for potato production since all cultivars in this site had superior marketable tuber yields. 'Taurus' was the most stable and adaptable cultivar across trial sites (wide adaptation), whilst 'Hermes' and 'Snowden' were more adapted under Opiki and Hastings conditions (specific adaptation), respectively. As established in this study, heat and drought stresses have significant effects on the morpho-physiology, yield, and tuber quality of commercial potato cultivars in New Zealand. [ABSTRACT FROM AUTHOR]

Drought stress is an unavoidable factor that exists in a variety of habitats which hinders the production, quality, and energy of plant biomass. Drought conditions result in oxidative stress in plants due to excessive reactive oxygen species (ROS) produced as a result of low CO2 which interferes with plant photosynthetic capacity. Consequently, during periods of drought stress, the transport of nutrients and the mass flow of water - soluble nutrients like nitrate, sulfate, calcium, and silicon is reduced. The application of traditional approaches in developing drought-tolerant crops is a time-consuming process, and the use of advanced biotechnology for agricultural development is still viewed with caution. The use of plant growth-promoting rhizobacteria (PGPR) as a cost-effective and environment friendly strategy can be adopted to enhance crop development in drought stress conditions. The synthesis of 1-aminocyclopropane-1-carboxylate (ACC) deaminase promotes plant nutrient uptake by metabolizing plant ACC, consequently preventing the accumulation of ethylene. The PGPR enhances the plant's defense mechanisms, leading to higher relative water content, decreased oxidation products and increased levels of antioxidants and osmo protectants within the plants. The synthesis of exopolysaccharides (EPS) also improves the soil's capacity to retain water. Osmolyte synthesis is increased by PGPR and effectively mitigates ROS's harmful effects to assist the plant growth. For the manufacture of bio-fertilizers to minimize the negative impacts of drought stress on crops grown in dry environments, multifaceted PGPR are promising options. This review outlines potential future directions for sustainable agricultural production and suggest s techniques to improve their effectiveness as bio-inoculants in field settings. [ABSTRACT FROM AUTHOR]

Climate change is a situation that causes an increase in global temperature due to the increase in greenhouse gases in the atmosphere and the effect of natural processes. This temperature increase causes many environmental effects around the world. Two of these effects are ultraviolet-B (UV-B) radiation, a harmful type of electromagnetic light from the sun, and severe water shortages called droughts. In this study, we tried to determine how the wood structure (properties of libriform fibers and various mechanical properties) and plant photosynthesis parameters of Acer negundo and Acer pseudoplatanus species changes under two droughts (moderate and severe) and UV-B (low [8 kJ m−2 h−1] and high [12 kJ m−2 h−1]) stresses. Also, leaf gas exchange parameters (net photosynthesis, stomatal conductance, transpiration rate, and water use efficiency) were evaluated under these stressors. As a result, it was observed that fiber wall thickness decreased in seedlings exposed to both drought and UV-B radiation in both species. It was determined that plant gas exchange parameters decreased with drought stress but did not vary much with UV-B stress; the amount of plant transpiration decreased with the effect of drought and increased with the amount of UV-B radiation. The plant may have reduced transpiration to reduce the effect of drought stress and increased transpiration to use UV-B radiation for plant growth. [ABSTRACT FROM AUTHOR]

Sorghum is an important cereal in many parts of the world, but water stress is a major constraint to its yield. In response to water stress, plants can modify gene expression, leading to a variety of changes in biochemical and physiological pathways. In the present study, 32 accessions of sorghum were screened for drought tolerance at the seedling stage based on morphometric traits. After 14 days of water stress, the most-tolerant (NGB01435) and susceptible (AKZ-NrSOR1013) accessions were assessed for drought-related gene expression research. The result of the morphometric attributes showed variation in seedling growth among the accessions. Also, significant correlations exist among the evaluated attributes, and the clustering pattern revealed genetic diversity in the accessions. The analysis of Ct values across the samples revealed differential expression of the reference gene (ELF4α) and the target genes (SNAC1 and DREB1A). SNAC1 is a stress-responsive NAC superfamily transcription factor, while DREB1A is a dehydration-responsive element binding protein 1 (DREB1)/C-repeat-binding factor (CBF), both of which are involved in stress regulation in plants. Both target genes had lower expression under stress in the tolerant accession (NGB01435) and were upregulated in the susceptible accession (AKZ-NrSOR1013). This study concluded that accessions respond differentially to water stress in terms of growth and development; the downregulation of both SNAC1 and DREB1A is critical to the mechanism involved in the water stress modulation to confer resistance in sorghum seedlings under water deficit conditions. [ABSTRACT FROM AUTHOR]

Chickpea is an important legume, which is mainly planted in the dry season. Drought stress at the end of the season during flowering and pod formation is one of the most important factors limiting production in chickpea. We aimed to investigate the effect of drought stress on yield and related traits, as well as to evaluate and determine the most appropriate indices of drought tolerance in chickpeas. Twenty chickpea genotypes (in 2017–2019) were used as material. The experiment was set up as randomized complete block design under normal and drought conditions. The effect of drought and genotype was significant for all traits. Drought reduced all traits except unfilled pod percentage and canopy temperature traits. Shoot length density and 100-seed weight had the highest direct and positive effect, while days to flowering had the highest negative and significant effect on grain yield. Sixteen previous different drought tolerance indices and two new indices namely: Tolerance Ranking Index (TRI) and Relative Tolerance Index (RTI) were estimated based on grain yield in normal and drought conditions. Based on the results, Harmonic Mean (HAM), Geometric Mean Productivity (GMP), Stress Tolerance Index (STI), TRI and RTI were the best indices to identify tolerant genotypes. TRI and RTI exhibited a positive significant simple correlation with Yp, Ys, HAM, STI and GMP, but their correlations with SSI and Yield Reduction index (YR) were significantly negative. TRI and RTI are powerful to select tolerant genotypes and can be used as indices in the development of QTL populations, due to their association with yield stability under both normal and drought conditions. Also, all superior drought stress indices identified ILC1799, ILC482 and FLIP90-96 as the most tolerant genotypes. [ABSTRACT FROM AUTHOR]

Water shortage in dry and semi-arid regions is a major agricultural challenge. This study investigated the performance of ten imported monogerm sugar beet varieties under continuous deficiency irrigation using a drip system on a private farm in the Wadi El-Natrun region, El-Beheira Governorate, Egypt, during two growing seasons, 2021/2022 and 2022/2023. The study utilized a novel method, a crossbar graph, to effectively visualize statistical data. The results showed significant interaction effects between sugar beet varieties and water deficit levels for all traits, indicating varying responses of the varieties to different levels of drought stress (75% and 55%). Drought stress levels (75% and 55%) had an adverse effect on the root yield of the ten varieties of sugar beet that were investigated. The exploratory factor analysis was applied to investigate and describe the relationship between ten different varieties of sugar beet and water stress treatments. Varieties Symbol, Stikhiyn, Volua, and Klara were characterized as moderate and tolerant with high performance, and they received the highest score in factor analysis. These varieties are recommended for cultivation under moderate and severe stress conditions. Factor analysis scores can be used as selection criteria for sugar beet varieties. [ABSTRACT FROM AUTHOR]

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In order to detect markers for drought stress tolerance, field experiments in Ethiopia were conducted for three years at two naturally drought-prone locations and two optimum moisture locations using 239 Ethiopian barley landraces and 21 barley breeding lines. Furthermore, a climate chamber experiment applying drought stress at different water regimes (70% soil water capacity (WC) for control and 20% WC for drought stress conditions) after flowering was conducted for selected 196 accessions. Results revealed reduced grain biomass by 47% and 80% under field and climate chamber conditions, respectively, as well as significantly (p < 0.05) reduced days to maturity and plant height, in both experimental designs. Based on 10,644 SNP markers, GWAS was conducted to identify marker trait associations (MTA) for drought stress tolerance. For days to maturity, relative chlorophyll content, plant height, number of seeds per spike, thousand kernel weight, and harvest index under field and climate chamber drought stress treatments, 58 significant MTAs were identified. In total, 41.4% of the MTAs were located on chromosome 2H, of which one is very close to the Ppd-H1 flowering locus. These findings underpin the importance of this genome region for drought tolerance. Another MTA on chromosome 1H was detected for days to maturity under field drought stress treatment in the vicinity of the known flowering time ELF3 gene. Additionally, 13 and 3 Ethiopian landraces that tolerate severe and moderate drought stress in climate chamber and field experiments were identified, respectively, using drought indices. The results highlight the tolerance of Ethiopian landraces to different levels of drought stress as well as their potential to be considered in future barley improvement programs. [ABSTRACT FROM AUTHOR]

Main conclusion: In the present review, we discussed the detailed signaling cascades via membrane transporters that confer plant tolerance to abiotic stresses and possible significant use in plant development for climate-resilient crops. Plant transporters play significant roles in nutrient uptake, cellular balance, and stress responses. They facilitate the exchange of chemicals and signals across the plant's membrane by signal transduction, osmotic adjustment, and ion homeostasis. Therefore, research into plant transporters is crucial for understanding the mechanics of plant stress tolerance. Transporters have potential applications in crop breeding for increased stress resistance. We discuss new results about various transporter families (ABC, MATE, NRAMP, NRT, PHT, ZIP), including their functions in abiotic stress tolerance and plant development. Furthermore, we emphasize the importance of transporters in plant responses to abiotic stresses such as drought, cold, salt, and heavy metal toxicity, low light, flooding, and nutrient deficiencies. We discuss the transporter pathways and processes involved in diverse plant stress responses. This review discusses recent advances in the role of membrane transporters in abiotic stress tolerance in Arabidopsis and other crops. The review contains the genes discovered in recent years and associated molecular mechanisms that improve plants’ ability to survive abiotic stress and their possible future applications by integrating membrane transporters with other technologies. Membrane transporters function to abiotic stress tolerance [ABSTRACT FROM AUTHOR]

Main conclusion: TaZAT8-5B, a C2H2 zinc finger protein transcription factor, positively regulates drought tolerance in transgenic Arabidopsis. It promotes root growth under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. C2H2 zinc finger proteins (C2H2-ZFPs) represent the largest but relatively unexplored family of transcription factors in plants. This is particularly evident in wheat, where the functions of only a few C2H2-ZFP genes have been confirmed. In this study, we identified a novel C2H2-ZFP gene, TaZAT8-5B. This gene shows high expression in roots and flowers and is significantly induced by heat, drought, and salt stress. Under drought stress, overexpressing TaZAT8-5B in Arabidopsis resulted in increased proline content and superoxide dismutase (SOD) activity in leaves. It also led to reduced stomatal aperture and water loss, while inducing the expression of P5CS1, RD29A, and DREB1A. Consequently, it alleviated drought stress-induced malondialdehyde (MDA) accumulation and improved drought tolerance. Additionally, TaZAT8-5B promoted lateral root initiation under mannitol stress and enhanced both lateral and primary root growth under long-term drought stress. Moreover, TaZAT8-5B was induced by indole-3-acetic acid (IAA). Overexpressing TaZAT8-5B under drought stress significantly inhibited the expression of auxin signaling negative regulatory genes IAA12 and IAA14. Conversely, downstream genes (ARF7, LBD16, LBD18, and CDKA1) of IAA14 and IAA12 were upregulated in TaZAT8-5B overexpressing plants compared to wild-type (WT) plants. These findings suggest that TaZAT8-5B regulates root growth and development under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. In summary, this study elucidates the role of TaZAT8-5B in enhancing drought tolerance and its involvement in root growth and development through the auxin signaling pathway. These findings offer new insights into the functional analysis of homologous genes of TaZAT8-5B, particularly in Gramineae species. [ABSTRACT FROM AUTHOR]

Under light with a low proportion of far-red (FR) light, plants perceive themselves as growing in open places, which may lead them to increase leaf hydraulic conductance (Kleaf) to cope with the higher water demand associated with increased light intensities. We evaluated Kleaf of cucumber (Cucumis sativus L.) seedlings that had been acclimatized to light with different proportions of FR. Kleaf tended to increase with decreasing FR light. Kleaf and leaf vein length density were positively correlated, indicating that increased Kleaf caused by low FR light may have been caused by changes in leaf vein structure. To clarify whether acclimatization to low-FR light can improve tolerance to high evaporative demand, we evaluated changes in stomatal conductance (gs), quantum yield of photosystem II (ΦPSII), and leaf water potential (Ψleaf) when seedlings that had been acclimatized to light with FR light in the same proportion as sunlight (FR+) or light without FR light (FR−) were transferred to a high vapor-pressure deficit (VPD) condition. After transfer to high VPD, gs and Ψleaf of the seedlings decreased in all treatment groups, but the decrease was smaller in the FR− seedlings. After transfer to high VPD, ΦPSII decreased significantly in the FR+ seedlings, but not in the FR− seedlings. These findings suggest that the changes in stress tolerance induced by FR light may be partly mediated by changes in Kleaf. Our results also indicate a potential new technique for mitigating drought stress in horticultural crops by controlling FR light. [ABSTRACT FROM AUTHOR]

ABSTRACT Crocus sativus L., known as saffron, is one of the major crops among ornamental and medicinal aromatic plants. Polyethylene glycol (PEG) 6000 is one of the well‐known and efficient simulators used for this purpose. In this study, saffron corms were cultivated in pots containing perlite, and the PEG 6000 solution was applied at 5%, 10% and 15% concentrations. A HS‐SPME‐GC–MS system was used to elucidate volatiles of saffron flowers, and a total of 28 volatiles was detected. Safranal was measured as the most dominant volatile compound in saffron flowers, and the release of marker volatiles was dramatically increased with the increasing PEG 6000 dosage. Eucarvone was found to be an important ketone compound, Phenethyl alcohol was found to be the most abundant volatile alcohol compound. Additionally, ketones pyrrole, lactone, esters and other sulphurous components increased with PEG 6000 application. According to the morphological observations, decreases were observed in plant dry weight (PDW), plant fresh weight (PFW), corm diameter (CD), daughter corm (DCN), and flower number (FN), between the control plants and those treated with PEG 6000. However, an increase was detected in root number (RN) and root length (RL). Leaf length (LL), on the other hand, increased with a 5% PEG application but decreased with higher concentrations. [ABSTRACT FROM AUTHOR]

Introduction: Mitochondria are essential organelles in eukaryotic cells, producing ATP through the electron transport chain to supply energy for cellular activities. Beyond energy production, mitochondria play crucial roles in cellular signaling, stress responses, and the regulation of reactive oxygen species. In plants, mitochondria are one of the keys to responding to environmental stresses which can significantly affect crop productivity, particularly in crops like wheat. RNA editing, a post-transcriptional RNA modification process in mitochondria, is linked to regulating these stress responses. Methods: This study explores RNA editing patterns in the nad9 gene of wheat drought-tolerant (Giza168) and drought-sensitive (Gemmiza10) wheat cultivars under drought stress to understand plant adaptation mechanisms. RNA-seq data for these cultivars were analyzed using CLC Genomic Workbench to identify RNA editing sites in the nad9 gene, examining subsequent amino acid changes and predicting secondary structure modifications. These RNA editing sites were validated using qRT-PCR on drought-treated seedlings at 0, 2, and 12 hours post-treatment. Protein models were generated using AlphaFold, with functional predictions and structure verification conducted using various bioinformatics tools to investigate the effect of RNA editing on protein level. Results: The results showed significant RNA editing events, especially C-to-T conversions, in the nad9 gene across different drought exposure times. Giza168 had 22 editing sites, while Gemmiza10 had 19, with several showing significant differences between control and stress conditions. RNA editing influenced the NAD9 protein's secondary structure, particularly beta sheets, and 3D modeling highlighted the structural impacts of these edits. The N-terminal region of NAD9 contained important regulatory motifs, suggesting a complex regulatory environment. Discussion: This study reveals key editing sites that differ between drought-tolerant and sensitive wheat cultivars, impacting NAD9 protein structures and highlighting the role of RNA editing in enhancing drought resilience. Additionally, the study suggests potential regulatory mechanisms, including phosphorylation and ubiquitination that influence mitochondrial stability and function. [ABSTRACT FROM AUTHOR]

Fibrillins (FBNs), highly conserved plastid lipid-associated proteins (PAPs), play a crucial role in plant physiology. These proteins, encoded by nuclear genes, are prevalent in the plastoglobules (PGs) of chloroplasts. FBNs are indispensable for maintaining plastid stability, promoting plant growth and development, and enhancing stress responses. The conserved PAP domain of FBNs was found across a wide range of photosynthetic organisms, from plants and cyanobacteria. FBN families are classified into 12 distinct groups/clades, with the 12th group uniquely present in algal–fungal symbiosis. This mini review delves into the structural attributes, phylogenetic classification, genomic features, protein–protein interactions, and functional roles of FBNs in plants, with a special focus on their effectiveness in mitigating abiotic stresses, particularly drought stress. [ABSTRACT FROM AUTHOR]

SUMMARY As a crucial forage grass, Leymus chinensis plays significant roles in soil and water conservation owing to its robust stress resistance. However, the underlying molecular mechanisms of its stress tolerance remain unclear. In this study, a novel gene, designated as LcASR (Abiotic Stress Resistance in Leymus chinensis), imparting resilience to both high light and drought, was identified. Under normal growth conditions, heterologous overexpression of LcASR in Arabidopsis (HO lines) showed no significant difference in appearance compared to wild‐type. Nevertheless, HO lines accumulate significantly higher chlorophyll content during the dark‐to‐light transition compared to the wild‐type, indicating that the LcASR protein participates in chlorophyll synthesis during chloroplast development. Meanwhile, transgenic Arabidopsis and L. chinensis plants exhibited resistance to abiotic stresses such as high light and drought. Photosystem complexes analysis revealed that LHCII proteins remained stable within their respective complexes during high light stress. We hypothesize that LcASR may play a role in fine tuning of chlorophyll synthesis to enable plant adaptation to diverse stress conditions. Moreover, overexpression of LcASR in L. chinensis led to agronomically valuable traits such as deeper green color, higher biomass accumulation, prolonged withering period, and extended grazing durations. This study uncovers a novel gene in L. chinensis that enhances forage yield and provides valuable genetic resources for sheepgrass breeding. [ABSTRACT FROM AUTHOR]

The impact of climate change on agricultural production is apparent due to declining irrigation water availability vis-à-vis rising drought stress, particularly affecting summer crops. Growing evidence suggests that zinc (Zn) supplementation may serve as a potential drought stress management strategy in agriculture. Field studies were conducted using soybean (Glycine max var. Saba) as a model crop to test whether foliar application of zinc oxide nanoparticles (ZnO-NPs) or conventional Zn fertilizer (ZnSO4) would mitigate drought-related water stress and improve soybean yield. Each fertilizer was foliar applied twice at a two-week interval during the flowering stage. Experiments were concurrently conducted under non-drought conditions (70% field capacity) for comparison. Results showed drought significantly reduced relative water content, chlorophyll-a, and chlorophyll-b in untreated control plants by 35.7%, 47.7%, and 41.4%, respectively, compared to non-drought conditions (p < 0.05). Under drought conditions, ZnO-NPs (200 mg Zn/L) led to 33.1% and 20.7% increase in chlorophyll-a and chlorophyll-b levels, respectively, compared to ZnSO4 at 400 mg Zn/L. Likewise, catalase, peroxidase and superoxide dismutase activities increased by 62.6%, 39.5% and 28.5%, respectively, with ZnO-NPs (200 mg Zn/L) under drought compared to non-drought conditions. Proline was significantly increased under drought but was remarkably suppressed (~ 54% lower) with ZnO-NPs (200 mg Zn/L) treatment. More importantly, the highest seed yield was observed with ZnO-NPs (200 mg Zn/L) treatment under drought (39% higher than untreated control) and non-drought (79.4% higher than control) conditions. Overall, the findings suggest that ZnO-NPs could promote seed yield in soybean under drought stress via increased antioxidant activities, increased relative water content, decreased stress-related proline content, and increased photosynthetic pigments. It is recommended that foliar application of 200 mg Zn/L as ZnO-NPs could serve as an effective drought stress management strategy to improve soybean yield. [ABSTRACT FROM AUTHOR]

Understanding the intricate relationship between drought stress and corn yield is crucial for ensuring food security and sustainable agriculture in the face of climate change. This study investigates the subtle effects of drought stress on corn physiological, morphological, and spectral characteristics at different growth stages, in order to construct a new drought index to characterize drought characteristics, so as to provide valuable insights for maize recovery mechanism and yield prediction. Specific conclusions are as follows. Firstly, the impact of drought stress on corn growth and development shows a gradient effect, with the most significant effects observed during the elongation stage and tasseling stage. Notably, Soil and Plant Analyzer Development (SPAD) and Leaf Area Index (LAI) are significantly affected during the silking stage, while plant height and stem width remain relatively unaffected. Secondly, spectral feature analysis reveals that, from the elongation stage to the silking stage, canopy reflectance exhibits peak–valley variations. Drought severity correlates positively with reflectance in the visible and shortwave infrared bands and negatively with reflectance in the near-infrared band. Canopy spectra during the silking stage are more affected by moderate and severe drought stress. Thirdly, LAI shows a significant positive correlation with yield, indicating its reliability in explaining yield variations. Finally, the yield-related drought index (YI) constructed based on Convolutional Neural Network (CNN), Random Forest (RF) and Multiple Linear Regression (MLR) methods has a good effect on revealing drought characteristics (R = 0.9332, p < 0.001). This study underscores the importance of understanding corn responses to drought stress at various growth stages for effective yield prediction and agricultural management strategies. [ABSTRACT FROM AUTHOR]

Betula luminifera, an indigenous hardwood tree in South China, possesses significant economic and ecological value. In view of the current severe drought situation, it is urgent to enhance this tree's drought tolerance. However, traditional artificial methods fall short of meeting the demands of breeding efforts due to their inefficiency. To monitor drought situations in a high-throughput and automatic approach, a deep learning model based on phenotype characteristics was proposed to identify and classify drought stress in B. luminifera seedlings. Firstly, visible-light images were obtained from a drought stress experiment conducted on B. luminifera shoots. Considering the images' characteristics, we proposed an SAM-CNN architecture by incorporating spatial attention modules into classical CNN models. Among the four classical CNNs compared, ResNet50 exhibited superior performance and was, thus, selected for the construction of the SAM-CNN. Subsequently, we analyzed the classification performance of the SAM-ResNet50 model in terms of transfer learning, training from scratch, model robustness, and visualization. The results revealed that SAM-ResNet50 achieved an accuracy of 1.48% higher than that of ResNet50, at 99.6%. Furthermore, there was a remarkable improvement of 18.98% in accuracy, reaching 82.31% for the spatial transform images generated from the test set images by applying movement and rotation for robustness testing. In conclusion, the SAM-ResNet50 model achieved outstanding performance, with 99.6% accuracy and realized high-throughput automatic monitoring based on phenotype, providing a new perspective for drought stress classification and technical support for B. luminifera-related breeding work. [ABSTRACT FROM AUTHOR]

Drought tolerance varies among different peanut (Arachis hypogaea L.) cultivars. Here, drought responses of two cultivars, Huayu 22 (HY22) with drought tolerance and Fuhua 18 (FH18) with drought sensitivity, were compared at the morphological, physiological, biochemical, photosynthetic, and transcriptional levels. Drought stress caused wilting and curling of leaves, bending of stems, and water loss in both cultivars. There was an increase in malondialdehyde (MDA) content under prolonged drought stress, more so in FH18. But the levels of reactive oxygen species (H2O2) and lipid peroxidation were low in HY22. The activities of superoxide dismutase (SOD), peroxidase (POD), and glutathione reductase (GR) were considerably elevated, corresponding with rapid increases in the accumulation of soluble proteins, soluble sugars, and proline. Transcriptional sequencing showed gene expression varied seriously in HY22, which was upregulated in both stems of two cultivars, though downregulation was less pronounced in HY22. KEGG pathway analysis revealed significant enrichment in four leaf and six stem pathways. Additionally, core genes relating to photosynthesis, carbon fixation, proline synthesis, and sucrose and starch synthesis pathways were identified by correlation analysis. Those gene expressions were variously upregulated in stems of two cultivars, especially in HY22, giving a novel view of the shoot as a whole participating in stress response. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Aim Methods Results Conclusion Drought stress (DS) impedes plant growth and development by impairing the uptake of nutrients, such as magnesium, which is central to many physiological processes, particularly photosynthesis. Leaf application was proposed to be an effective strategy to compensate for inadequate Mg2+ supply from the nutrient solution.The present study is designed to investigate the role of Mg2+ leaf application in ameliorating leaf anatomy and chloroplast ultrastructure changes in faba beans grown under DS.Hydroponically grown plants were subjected to DS under various levels of Mg2+, i.e. sufficient (0.5 mM), deficient (0 mM), and leaf‐application (250 mM). Light and transmission electron microscopy (TEM) were conducted to examine leaf anatomy and ultrastructural changes.Mg2+ deficiency alone and under DS significantly affected plant biomass and photosynthesis. Additionally, sucrose concentration, oxidative stress, and lipid peroxidation were increased. Accordingly, the excessive deposition of photoassimilates in source organs due to the inhibition of phloem loading results in a disruption of the thylakoid structures leading to chloroplast damage. In the current study leaf application of Mg2+ partially ameliorated physiological functions, most notably chlorophyll concentration, photosynthesis and transpiration rate, plant biomass, and preservation of ultrastructure of the chloroplast.Although the Mg application via roots enhanced drought tolerance, compared to Mg2+ leaf application. However, Mg2+ leaf application was proven to be an efficient strategy in mitigating DS in field trials. Therefore, Mg2+ foliar application should be prioritized for further investigation under relevant environmental stress conditions. [ABSTRACT FROM AUTHOR]

Summary Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing‐retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance‐based detection of the 535‐nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy‐based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications. [ABSTRACT FROM AUTHOR]

Drought stress can markedly reduce plant growth and development, leading to considerable yield losses in sweet basil (Ocimum basilicum L.). Individual application of silicon (Si) and salicylic acid (SA) has the potential to mitigate the detrimental effects of drought stress; however, their combined effect is largely unknown. The aim of this study was to evaluate the efficacy of Si and SA, both independently and in concert, in mitigating the deleterious impacts of drought stress on sweet basil plants. A factorial experiment was implemented using a completely randomized design, incorporating soil application of three Si levels (0, 30, and 60 kg ha–1), foliar application of three SA levels (0, 100, and 200 mg L–1), and three soil moisture levels (50, 75, and 100% field capacity 'FC'). Leaf area, shoot dry matter, leaf yield, irrigation water productivity, net photosynthetic rate, and stomatal conductance were declined by 54–78%, 55–66%, 77–84%, 55–68%, 42–70%, and 73–92%, respectively, at 50% FC in contrast to conditions at 100% FC, while electrolyte leakage, free proline concentration, total phenol concentration, and total flavonoid concentration were increased by 77–130%, 173–330%, 87–148%, and 101–169%, respectively, across Si and SA doses. The treatment of 60 kg Si ha–1 in conjunction with 100 mg SA L–1 emerged as the most efficacious treatment. This combination resulted in a 174% augmentation in leaf area, a 91% enhancement in shoot dry matter, a 98% increase in leaf yield, a 63% increase in irrigation water productivity, a 28% rise in leaf relative water content, and a 112% increase in total phenol concentration at 50% FC, when compared to plants grown under the same soil moisture level without Si and SA supplementation. Additionally, this treatment combination reduced electrolyte leakage by 26% compared to the plants not receiving Si and SA at 50% FC. The performance of plants under this combination at 75% FC was superior to that of the control plants even under optimal conditions at 100% FC for some parameters, underscoring the drought-mitigating potential of Si and SA in sweet basil. The combination of Si (60 kg ha–1) as a soil amendment and SA (100 mg L–1) applied as a foliar spray could be an effective strategy for improving the drought tolerance ability of sweet basil and enhancing its performance under both water-stressed and well-watered conditions. [ABSTRACT FROM AUTHOR]

Background: Codonopsis pilosula (Campanulaceae) is a traditional herbal plant that is widely used in China, and the drought stress during the seedling stage directly affects the quality, ultimately impacting its yield. However, the molecular mechanisms underlying the drought resistance of C. pilosula seedlings remain unclear. Method: Herein, we conducted extensive comparative transcriptome and physiological studies on two distinct C. pilosula cultivar (G1 and W1) seedlings subjected to a 4-day drought treatment. Results: Our findings revealed that cultivar G1 exhibited enhanced retention of proline and chlorophyll, alongside a marked elevation in peroxidase activity, coupled with diminished levels of malondialdehyde and reduced leaf relative electrolyte leakage compared with cultivar W1. This suggested that cultivar G1 had relatively higher protective enzyme activity and ROS quenching capacity. We discerned a total of 21,535 expressed genes and identified 4,192 differentially expressed genes (DEGs) by RNA sequencing (RNA-seq). Our analysis revealed that 1,764 DEGs unique to G1 underwent thorough annotation and functional categorization utilizing diverse databases. Under drought conditions, the DEGs in G1 were predominantly linked to starch and sucrose metabolic pathways, plant hormone signaling, and glutathione metabolism. Notably, the drought-responsive genes in G1 were heavily implicated in hormonal modulation, such as ABA receptor3-like gene (PYL9), regulation by transcription factors (KAN4 , BHLH80 , ERF1B), and orchestration of drought-responsive gene expression. These results suggest that cultivar G1 possesses stronger stress tolerance and can better adapt to drought growing conditions. The congruence between qRT-PCR validation and RNA-seq data for 15 DEGs further substantiated our findings. Conclusion: Our research provides novel insights into the physiological adaptations of C. pilosula to arid conditions and lays the groundwork for the development of new, drought-tolerant C. pilosula cultivars. [ABSTRACT FROM AUTHOR]

Nitrogen is a critical nutrient vital for crop growth. However, our current understanding of nitrogen use efficiency (NUE) under drought remains inadequate. To delve into the molecular mechanisms underlying NUE under drought, a transcriptome and physiological co-expression analysis was performed in rice, which is particularly sensitive to drought. We conducted a pot experiment using rice grown under normal irrigation, mild drought stress, and severe drought stress. Compared to the normal treatment, drought stress led to a significant reduction in NUE across growth stages, with decreases ranging from 2.18% to 31.67%. Totals of 4,424 and 2,452 genes were identified as NUE-related DEGs that showed differential expressions (DEGs) and significantly correlated with NUE (NUE-related) under drought in the vegetative and reproductive stages, respectively. Interestingly, five genes involved in nitrogen metabolism were found in the overlapped genes of these two sets. Furthermore, the two sets of NUE-related DEGs were enriched in glyoxylate and dicarboxylate metabolism, as well as carbon fixation in photosynthetic organisms. Several genes in these two pathways were identified as hub genes in the two sets of NUE-related DEGs. This study offers new insights into the molecular mechanism of rice NUE under drought in agricultural practices and provides potential genes for breeding drought-resistant crops with high NUE. [ABSTRACT FROM AUTHOR]

Sexual reproduction through seeds is an effective way to renew plant populations and increase their genetic diversity, but seed germination process is complicated and relatively difficult due to the restriction of environmental conditions. Wetland plants that reproduce sexually through seeds may be affected by changes in moisture and temperature. This study aims to explore the ecological adaptation strategies of seed germination of Lilium concolor var. megalanthum under different hydrothermal conditions. Controlled experiments were conducted to investigate the germination performance of L. concolor var. megalanthum seeds at different temperatures (10°C, 15°C, 20°C, 25°C, and 30°C) and simulated drought stress conditions using PEG-6000 solutions (0%, 5%, 10%, 15%, and 20%). The results showed that temperature, drought stress, and their interaction significantly affected the days to first germination, germination percentage, coefficient of germination rate, germination energy, germination index, and vigor index of seeds (p <0.01). The germination percentage, germination index, and vigor index of seed were significantly higher at 25°C compared to other temperatures (p <0.01). The interaction between low temperature and drought stress significantly delayed the days to first germination. The inhibition of drought stress on seed germination was enhanced by PEG-6000 solution under high temperature. Under the conditions of 25°C and 5% PEG-6000 solution concentration, seeds of L. concolor var. megalanthum exhibited optimal germination parameters. At 10°C and 15°C, the seeds exhibited the highest tolerance to PEG-6000-simulated drought stress. Rehydration germination results showed that extreme temperatures and drought stress conditions inhibit seed germination of L. concolor var. megalanthum without damaging seed structure. The germination pattern of seeds under variable temperature and drought stress conditions reflects their adaptive strategies developed over long-term evolution to cope with the environmental conditions. [ABSTRACT FROM AUTHOR]

Drought stress significantly threatens plant ecosystems, particularly amid climate change. Understanding the mechanisms of plant resilience is essential for developing strategies to mitigate water scarcity effects on agroforestry. This study evaluated morphological, physiological and biochemical traits in Argania spinosa seedlings from four provenances (Berkane (BRK), Essaouira (ESS), Agadir (AGD) and Bouizakarne (BZK)) subjected to severe drought for three weeks. The results showed significant inter-provenance variation in the traits examined. Root dry biomass increased markedly across all provenances, with the highest increase observed in BZK (117.9%). Leaf water potential significantly decreased under drought stress, but relative water content (RWC) remained stable. Proline accumulation was significant in stressed seedlings, especially in ESS (163.4%), while total soluble sugars significantly increased only in BRK (26.6%). All provenances showed a significant reduction in chlorophyll a and b, except for BRK. Correlations among all studied traits varied significantly in both number and significance between drought stress and non-stress conditions. Canonical discriminant analysis revealed distinct separation among the provenances, indicating intra-species variability in drought responses. Key traits like dry biomass, collar diameter, basic leaf water potential, RWC and proline were identified as important indicators of drought tolerance, suggesting their utility in selecting the most resilient A. spinosa provenance. [ABSTRACT FROM AUTHOR]

Introduction: Melatonin, a tryptophan-derived indoleamine metabolite with important roles in plant growth and defense, has recently been regarded as a new plant hormone. Maize is one of the most important cereal crops in the world. Although the melatonin receptor gene, ZmPMTR1 , has already been identified, the genetic basis of melatonin biosynthesis in maize has still not been elucidated. Serotonin N-acetyltransferase (SNAT) is the enzyme that converts serotonin to N-acetylserotonin (NAS) or 5-methoxytryptamine (5MT) to melatonin in Arabidopsis and rice, but no SNAT encoding gene has been identified yet in maize. Methods: The bioinformatics analysis was used to identify maize SNAT genes and the enzyme activity of the recombinant proteins was determined through in vitro assay. The expression levels of ZmSNAT1 and ZmSNAT3 under drought and heat stresses were revealed by public RNA-seq datasets and qRT-PCR analysis. Results: We first identified three maize SNAT genes, ZmSNAT1, ZmSNAT2, and ZmSNAT3, through bioinformatics analysis, and demonstrated that ZmSNAT2 was present in only eight of the 26 cultivars analyzed. We then determined the enzyme activity of ZmSNAT1 and ZmSNAT3 using their recombinant proteins through in vitro assay. The results showed that both ZmSNAT1 and ZmSNAT3 could convert serotonin to NAS and 5-MT to melatonin. Recombinant ZmSNAT1 catalyzed serotonin into NAS with a higher catalytic activity (K m, 8.6 mM; V max, 4050 pmol/min/mg protein) than ZmSNAT3 (K m, 11.51 mM; V max, 142 pmol/min/mg protein). We further demonstrated that the 228th amino acid Tyr (Y228) was essential for the enzymatic activity of ZmSNAT1. Finally, we revealed that the expression of ZmSNAT1 and ZmSNAT3 varied among different maize cultivars and different tissues of a plant, and was responsive to drought and heat stresses. Discussion: In summary, the present study identified and characterized the first two functional SNAT genes in maize, laying the foundation for further research on melatonin biosynthesis and its regulatory role in plant growth and response to abiotic stresses. [ABSTRACT FROM AUTHOR]

Drought and salinity are significant challenges to global food security. This study investigated the interactive impacts of Piriformospora indica inoculation with salinity and drought stresses on rice. Two greenhouse experiments were conducted. The first experiment evaluated two P. indica inoculation levels and three salinity levels (0-, 50-, and 100-mM sodium chloride), while the subsequent experiment assessed two inoculation levels under three drought intensities (25%, 50%, and 100% of available water content). P. indica spores were inoculated following optimized seed disinfection and germination processes. The shoot and root biomass under salinity stress were consistently higher in inoculated plants compared to controls. Sodium concentrations in shoots and roots exhibited an overall upward trend, with the trend being less pronounced in inoculated plants due to increased potassium uptake. Under salinity stress, nitrogen, magnesium, and calcium concentrations significantly increased in inoculated plants. With increasing salinity, there was a significant increase in catalase enzyme activity and soluble carbohydrate concentrations across all treatments, with a greater increase in inoculated plants. Plants under drought stress experienced reduced root and shoot biomass, but inoculated plants maintained higher biomass. Increasing drought stress led to decreased nitrogen, magnesium, and calcium concentrations in all treatments, with the reduction being less severe in inoculated plants. Catalase enzyme activity and carbohydrate increased with rising drought stress, with the increase being more pronounced in inoculated plants compared to non-inoculated ones. By promoting plant growth, nutrient uptake, and stress tolerance, P. indica inoculation has a significant potential to enhance crop productivity in extreme climate conditions. [ABSTRACT FROM AUTHOR]

Drought stress poses increasingly serious threats to agricultural production in the era of global climate change. Arbuscular mycorrhizal (AM) fungi are well-recognized biostimulants promoting plant tolerance to drought stress. Lipids are indispensable for AM fungal colonization, however, the involvement of lipid metabolism in the drought tolerance conferred by AM fungi is largely unknown. In this study, we inoculated Poncirus trifoliata (L.) with Rhizophagus irregularis DAOM197198 under no drought stress, medium drought stress and severe drought stress, with non-inoculation under respective treatments as control. Results indicated that AM fungal inoculation significantly promoted the drought tolerance of P. trifoliata (L.), with the effect size decreasing along with drought severity. Moreover, the effect size was significantly related to arbuscule abundance. Fatty acid profiling showed that the arbuscule abundance was determined by the AM-specific phospholipids (PLs), whose biosynthesis and delivery were inhibited by drought stress as revealed by qRT-PCR of FatM , RAM1 and STR / STR2. More interestingly, AM fungal inoculation increased the lipid allocation to total PLs and the unsaturation rate of total neutral lipids (NLs), probably indicating the involvement of non-AM-specific lipids in the increased drought tolerance. Taken together, our results demonstrate that lipid metabolism in AM mediates the increased drought tolerance conferred by AM fungal inoculation, with AM-specific and non-AM-specific lipids functioning therein in different ways. [ABSTRACT FROM AUTHOR]

Drought, a prevalent environmental stressor, has had significant consequences on soybean (Glycine max L.), notably impeding its growth and production. Therefore, it is crucial to gain insight into the regulatory responses of soybean plants exposed to drought stress during soybean flowering in the field. In this study, the cultivar 'Liaodou 15' was performed light drought (LD, 24.3% soil moisture content), moderate drought (MD, 20.6% soil moisture content) and severe drought (SD, 16.9% soil moisture content) treatments at flowering stages of soybean and then rehydrated (30% soil moisture content) until harvest. The yield-related indicators were measured and revealed that MD and SD treatments significantly reduced 6.3% and 10.8% of the 100-grain weight. Soybean plants subjected to three drought stresses showed that net photosynthetic rates were 20.8%, 51.5% and 71.8% lower in LD, MD and SD than that of CK. The WUE increased by 31.8%, 31.5% and 18.8% under three drought stress treatments compared to CK. In addition, proline content was 25.94%, 41.01% and 65.43% greater than that of CK under three drought stress treatments. The trend of the MDA content was consistent with that of the proline content. SOD activity was significantly increasing by 10.86%, 46.73% and 14.54% under three drought stress treatments. The activity of CAT in the SD treatment increased by 49.28%. All the indices recovered after rehydration. Furthermore, 54,78 and 51 different expressed metabolomics (DEMs) were identified in the LDCK/LD, MDCK/MD and SDCK/SD groups, respectively. There were 1,211, 1,265 and 1,288 different expressed genes (DEGs) were upregulated and 1,003, 1,819 and 1,747 DEGs were downregulated. Finally, combined transcriptomic and metabolomic analysis suggested that 437 DEGs and 24 DEMs of LDCK/LD group, 741 DEGs and 35 DEMs of MDCK/MD group, 633 DEGs and 23 DEMs of SDCK/SD group, were highly positively correlated in soybean plants under drought stress. Drought stress induced the expression of the PAO1, PAO4, PAO5 and P5CS genes to promote the accumulation of spermidine and proline. Our study elucidates the responses of drought-stressed soybean plants in the field and provides a genetic basis for the breeding of drought-tolerant soybean plants. [ABSTRACT FROM AUTHOR]

Summary The abscisic acid (ABA) signalling pathway plays a crucial role in plants’ response to drought stress. In this study, we aimed to characterize the impact of an ABA signalling module, which consisted of TaPYL9 and its downstream partners in Triticum aestivum, on plant drought adaptation. Our results showed that TaPYL9 protein contains conserved motifs and targets plasma membrane and nucleus after being sorted by the endoplasmic reticulum. In addition, TaPYL9 transcripts in both roots and leaves were significantly upregulated in response to drought stress. We conducted glucuronidase (GUS) histochemical staining analysis for transgenic plants carrying a truncated TaPYL9 promoter, which suggested that cis‐elements associate with ABA and drought response, such as ABRE, DRE and recognition sites MYB and MYC, regulating the gene transcription under drought conditions. Using protein interaction assays (i.e., yeast two‐hybrid, bimolecular fluorescence complementation (BiFC), co‐immunoprecipitation (Co‐IP) and in vitro pull‐down), we demonstrated interactions between the intermediate segment of TaPYL9, the intermediate segment of TaPP2C6, the N‐terminus of TaSnRK2.8 and the C‐terminus of the transcription factor TabZIP1 in wheat, indicating the involvement of TaPYL9 in the constitution of an ABA signalling module, namely TaPYL9/TaPP2C6/TaSnRK2.8/TabZIP1. Transgene analysis revealed that TaPYL9, TaSnRK2.8 and TabZIP1 positively regulated drought response, while TaPP2C6 negatively regulated it, and that these genes were closely associated with the regulation of stomata movement, osmolyte accumulation and ROS homeostasis. Electrophoretic mobility shift (EMSA) and transcriptioal activation assays indicated that TabZIP1 interacted promoters of TaP5CS2, TaSLAC1‐1 and TaCAT2 and activated transcription of these genes, which regulated proline biosynthesis, stomata movement and ROS scavenging upon drought signalling, respectively. Furthermore, we found that the transcripts of TaPYL9 and stress‐responsive genes were positively correlated with yields in wheat cultivars under field drought conditions. Altogether, our findings suggest that the TaPYL9‐involved signalling pathway significantly regulates drought response by modulating osmotic stress‐associated physiological processes in T. aestivum. [ABSTRACT FROM AUTHOR]

Drought poses a significant challenge to global crop productivity, necessitating innovative approaches to bolster plant resilience. Leveraging transgenic technology to bolster drought tolerance in crops emerges as a promising strategy for addressing the demands of a rapidly growing global populace. AtZAT10/STZ1, a C2H2-type zinc finger protein transcription factor has shown to significantly improve Arabidopsis' tolerance to various abiotic stresses. In this study, we reports that AtSTZ1 confers notable drought resistance in upland cotton (Gossypium hirsutum), amplifying cotton fiber yield under varying conditions, including irrigated and water-limited environments, in field trials. Notably, AtSTZ1-overexpressing transgenic cotton showcases enhanced drought resilience across critical growth stages, including seed germination, seedling establishment, and reproductive phases. Morphological analysis reveals an expanded root system characterized by an elongated taproot system, increased lateral roots, augmented root biomass, and enlarged cell dimensions from transgenic cotton plants. Additionally, higher contents of proline, chlorophyll, soluble sugars, and enhanced ROS-scavenging enzyme activities are observed in leaves of transgenic plants subjected to drought, underscoring improved physiological adaptations. Furthermore, transgenic lines exhibit heightened photosynthetic rate, increased water use efficiency, and larger stomatal and epidermal cell sizes, coupled with a decline in leaf stomatal conductance and density, as well as diminished transpiration rates compared to the wild type counterparts. Transcriptome profiling unveils 106 differentially expressed genes in transgenic cotton leaves post-drought treatment, including protein kinases, transcription factors, aquaporins, and heat shock proteins, indicative of an orchestrated stress response. Collectively, these findings underscore the capacity of AtSTZ1 to augment the expression of abiotic stressrelated genes in cotton following drought conditions, thus presenting a compelling candidate for genetic manipulation aimed at enhancing crop resilience. [ABSTRACT FROM AUTHOR]

Background: Zinc plays an important role in controlling both generations and also detoxifies free oxygen radicals that can damage membrane lipids and sulfhydryl groups. Zinc in particular has an action that prevents membrane damage induced by uperoxide radicals that produce NADPH oxidase. The use of zinc oxide (ZnO) nanoparticles in agriculture had a significant impact on crop growth regulation, improved quality and improved stress tolerance. Hence, the current study aimed to study the foliar spray effect of nanoscale zinc oxide (25 nm mean particle size) at different concentrations and chelated bulk zinc suphate (ZnSO4) and comparable control (unsprayed) in peanut to investigate the oxidative stress induction and enhanced antioxidant enzyme activity (SOD, POD, CAT) under conditions of water stress. Methods: The experimental design was a randomized block design with two water regimes as main treatments viz., well watered (WW) and water stress (WS) conditions, eight foliar sprays along with unsprayed treatment (control) as sub treatments and 3 replications. The eight foliar spray treatments, includes nanoscale ZnO concentrations @ 10, 20, 40, 50, 100, 300, 1000 ppm, chelated bulk ZnSO4 (EDTA based) @ 0.1% (recommended dose). The antioxidant enzyme activity (SOD, POD, CAT) under conditions of both WW and WS was determined in the lab using UV spectrophotometer. Result: The results of pot culture experiment revealed that nanoscale ZnO at a concentration of 50 ppm increased biomass and pod yield and promoted antioxidant enzyme activity under water stress and well watered conditions compared to chelated bulk ZnSO4. Nanoscale ZnO showed increased activity under lower concentrations and inhibitory activity at higher concentrations that highlights the need for careful use of these particles in agriculture. [ABSTRACT FROM AUTHOR]

[Objectives] The paper aimed to study the effects of drought stress on the physiological characteristics of grapes and the expression of stress-related genes. [Methods] The stress symptoms of the plants of ‘Shine Muscat' and ‘Kyoho' grape varieties, serving as test materials, were investigated through artificial drought stress simulation methods. Physiological indicators were measured, and principal component analysis and membership function analysis were conducted on these indicators for the two varieties under drought stress treatment. Furthermore, the expression levels of stress-related genes in the leaves were determined. [Results] The drought tolerance symptoms of both ‘Kyoho' and ‘Shine Muscat' were characterized by leaf wilting with leaf margin scorching at the base of the plant in the early period of drought stress, and green wilting and yellowing at the end of the stress period, but ‘Shine Muscat' showed drought stress symptoms earlier than those of ‘Kyoho'. With the prolongation of drought stress time, the leaf drought index of two grape varieties increased, the plant height and stem thickness showed a trend of increasing and then decreasing, the chlorophyll content declined, the activities of the peroxidase, superoxide dismutase, and ascorbate peroxidase showed a trend of increasing and then decreasing, and the quantum yield of the non-regulated energy dissipation in the PSⅡ, malondialdehyde content, proline content and soluble protein content showed an increasing trend. The average affiliation function values of ‘Kyoho' and ‘Shine Muscat' under drought stress were 0.47 and 0.46 respectively, and ‘Kyoho' was slightly more tolerant to drought stress than ‘Shine Muscat'. The RT-qPCR results showed that drought stress treatment significantly up-regulated the expression levels of the genes of VvPIP1, VvWRKY71, VvPP2C2 and VvRD22 in the leaves of two grape varieties. [Conclusions] Under drought stress, the response of ‘Shine Muscat' and ‘Kyoho' grape to drought stress was the same but the degree of response differed, and the drought tolerance of ‘Kyoho' was higher than that of ‘Shine Muscat'. [ABSTRACT FROM AUTHOR]

The need for plants resistant to abiotic stress now and in the future is predicted to be very high. It is related to extreme climate change and converting agricultural land into residential and industrial land. As Indonesia’s national strategic commodity, chili peppers require special attention when assembling chili peppers resistant to salinity and drought stress. New varieties of chili pepper plants resistant to saline and drought can be obtained through unconventional breeding (overexpression of the dehydrin gene). As a first step in assembling saline and drought-resistant chili plants, growth response and dehydrin gene expression tests were carried out from explants of chili pepper plants of the TM999 variety in vitro on salt and drought treatment media. This study aims to obtain information on the initial response to the growth and expression of the dehydrin gene from chili pepper plants of the TM999 variety before further research is carried out to increase the expression of the dehydrin gene through a molecular approach. The method used in this study is a complete randomized design with two treatments: Sodium chloride (NaCl) and polyethylene glycol (PEG-6000). The results obtained in this study showed that chili pepper varieties TM999 were more tolerant of drought stress than salinity based on several growth response data in both treatments. The analysis of dehydrin gene expression in both treatments showed that the gene expression was strongly influenced by the two strokes given. NaCl and PEG6000 treatments increased the dehydrin gene expression of chili pepper plants grown in vitro. [ABSTRACT FROM AUTHOR]

Competition in mesic sites and drought stress combined with short growing seasons in drier sites are key environmental factors along macroclimatic aridity gradients. They impose a triangular trade‐off for local adaptation. However, as experiments have rarely disentangled their effects on plant fitness, uncertainty remained whether mesic populations are indeed better competitors and drier populations better adapted to drought stress and short season length. Aridity differs also at microclimatic scale between north (more mesic) and south (more arid) exposed hill‐slopes. Little is known whether local adaptation occurs among exposures and whether south exposures harbor conspecifics better adapted to drier climates that could provide adaptive reservoirs under climate change. We sampled two Mediterranean annuals (Brachypodium hybridum, Hedypnois rhagadioloides) in 15 sites along a macroclimatic aridity gradient (89–926 mm rainfall) on corresponding north and south exposures. In a large greenhouse experiment, we measured their fitness under drought stress, competition, and short vs. long growing seasons. Along the macroclimatic gradient, mesic populations were better competitors under benign conditions. Drier populations performed no better under drought stress per se but coped better with the short growing seasons typical for drier macroclimates. At microclimatic scale, north exposure plants were slightly better competitors in H. rhagadioloides; in B. hybridum, south exposure plants coped better with drought under short season length. We demonstrate that local adaptation to drier macroclimates is trading‐off with competitive ability under benign conditions and vice‐versa. Drought escape via short life‐cycles was the primary adaptation to drier macroclimates, suggesting that intensified drought stress within the growing season under climate change challenges arid and mesic populations alike. Moreover, the drier microclimates at south exposures exhibited some potential as nearby reservoirs of drier‐adapted genotypes. This potential needs further investigation, yet may assist populations to persist under climate change and lessen the need for long‐distance migration. [ABSTRACT FROM AUTHOR]

Climate change significantly threatens crops, mainly through drought stress, affecting barley, which is essential for food and feed globally. Ten barley cultivars were evaluated under normal and drought stress conditions during the 2019/20 and 2020/21 seasons, focusing on traits such as days to heading and maturity, plant height, number of spikes m−2, spike length, 1000-kernel weight, and biological and grain yield. Drought stress significantly reduced most of these traits. The genotypes showed significant differences in their responses to irrigation treatments, with the interaction between seasons and cultivars also being significant for most traits. The grain yield and 1000-kernel weight were among the least affected traits under drought stress, respectively. Notably, Giza138 and Giza126 showed strong drought tolerance, suitable for drought-resilient breeding. In season one, Giza126, Giza134, and Giza138 yielded 13%, 9%, and 11%, respectively, while Giza135 and Giza129 showed higher reductions at 31% and 39%. In season two, Giza126, Giza134, and Giza138 had reductions of 14%, 10%, and 13%, respectively, while Giza135 and Giza129 again exhibited higher reductions at 31% and 38%. These cultivars also showed strong performance across various stress tolerance indices, including the MP, YSI, STI, GMP, and YI. Giza 134 demonstrated the lowest values for the SDI and TOL, indicating superior drought stress tolerance. On the other hand, Giza 129 and Giza 135 were the most sensitive to drought stress, experiencing significant reductions across critical traits, including 6.1% in days to heading, 18.37% in plant height, 28.21% in number of kernel spikes−1, 38.45% in grain yield, and 34.91% in biological yield. In contrast, Giza 138 and Giza 2000 showed better resilience, with lower reductions in the 1000-kernel weight (6.41%) and grain yield (10.61%), making them more suitable for drought-prone conditions. Giza 126 and Giza 132 also exhibited lower sensitivity, with minimal reductions in days to heading (2%) and maturity (2.4%), suggesting potential adaptability to water-limited environments. Giza 126 maintained the highest root lengths and had the highest stomatal conductance. Giza 138 consistently had the highest chlorophyll content, with SPAD values decreasing to 79% under drought. Despite leading in shoot length, Giza 135 decreased to 42.59% under drought stress. In conclusion, Giza 126 and Giza 138 showed adaptability to water-limited conditions with minimal impact on phenological traits. Giza 126 had the longest roots and highest stomatal conductance, while Giza 138 consistently maintained a high chlorophyll content. Together, they and Giza 134 are valuable for breeding programs to improve barley drought tolerance. [ABSTRACT FROM AUTHOR]