Drought Stress Research Articles

Grapevine and maize: Two guard cell shaped strategies to cope with repeated drought stress

Adaptation of crops to recurrent drought stress is crucial for maintaining agricultural productivity and achieving food security under changing climate. Guard cells, pivotal regulators of plant water usage and assimilation, are central to this adaptation process. However, the metabolic dynamics of guard cells under drought stress remain poorly understood, particularly in grapevine, a prominent crop grown in arid regions, and maize, a staple crop with substantial water requirements. In this study, differences in guard cells metabolism during drought stress of grapevine and maize were investigated by performing physiological and metabolomic analyses. Metabolomic analysis highlighted differential responses in amino acids and sugars, with grapevine guard cells displaying greater stability in amino acid and sugar signatures, while maize showed marked increases in sugar levels. These findings suggest two distinct adaptive strategies, a vigorous acclimation of guard cells, as observed in maize, and an attenuated acclimation of guard cells, shown in grapevine. Understanding these metabolic adjustments is helpful for enhancing drought resilience in agricultural systems.

LkERF6 enhances drought and salt tolerance in transgenic tobacco by regulating ROS homeostasis

The transcription factor Ethylene Responsive Factor (ERF) is crucial for responding to various environmental stressors. Proteins containing the ERF-associated amphiphilic repression (EAR) motif often inhibit gene expression. However, the functions of LkERF, an EAR motif-containing protein from Larix kaempferi, especially in reactive oxygen species (ROS) homeostasis, are not well understood. In the present research, we introduce a novel transcription factor, LkERF6, which contains an EAR motif and positively regulates gene expression, thereby enhancing drought and salt tolerance in tobacco. LkERF6 is classified within the ERF-B1 subfamily due to its conserved AP2/ERF domain and EAR motif. Subcellular localization assays demonstrated LkERF6 is primarily localized in the nucleus. Further analysis revealed that LkERF6 interacts with GCC and DRE elements and is significantly induced by NaCl and PEG6000. Moreover, LkERF6 transgenic tobacco plants exhibit lower ROS accumulation and higher levels of antioxidant enzyme activities. Additionally, correlation analysis identified a strong association between LkERF6 and three genes: LkSOD, LkCCS, and LkCAT. Y1H, EMAS, and DLR assays confirmed that LkERF6 directly interacts with the promoters of these genes through GCC-box and DRE-box to activate their expression. These findings shed new light on the function of EAR motif-containing transcription factors and highlight LkERF6’s crucial role in enhancing abiotic stress resistance by activating multiple ROS clearance genes.

Unveiling Bacillus rugosus CRI: A multi-stress tolerant endophyte revolutionizing rice resilience

The application of endophytes to mitigate stress in plants, particularly drought and salinity stress, has gained considerable attention, yet their role in rice remains underexplored. This study aimed to investigate the isolation and characterization of multi-stress-tolerant endophytic isolates with multiple plant growth-promoting attributes, including biocontrol potential against plant pathogens, from surface-sterilized leaf, stem, and root samples of various rice cultivars in Kerala. A total of 20 bacterial endophytes were isolated from rice plants and assessed for their plant growth-promoting (PGP) capabilities, biocontrol potential, and resilience to drought and salinity stress. Of these, 7 endophytic isolates exhibited notable PGP traits, and 3 demonstrated antifungal activity against Rhizoctonia solani and Fusarium oxysporum. Notably, only 3 endophytic isolates showed significant tolerance to drought conditions (−1.0 MPa) and salinity (150 mM), alongside strong growth-promoting abilities. The selected isolates significantly increased seed germination and seedling vigour (p ≤ 0.05), highlighting their effectiveness. Among these, the isolate CRI, identified as Bacillus rugosus through morphological, biochemical, and molecular (16S rRNA) analysis, stood out for its remarkable performance. Under stress conditions, rice seedlings treated with the multi-stress-tolerant CRI showed significant improved biomass, resilience, and enhanced biochemical processes, including better photosynthetic pigment levels and maintained membrane integrity. Field emission scanning electron microscopy (FE-SEM) confirmed the presence of these bacteria within the rice roots, underscoring their potential as a novel approach for enhancing stress tolerance and promoting rice growth. This study represents the first discovery of Bacillus rugosus as a potent multi-stress-tolerant endophyte, with dual benefits of promoting plant growth and exhibiting biocontrol activity. These findings pave the way for innovative strategies aimed at enhancing crop resilience and productivity, particularly in the face of increasing abiotic stressors in agricultural systems.

Using Marker-Assisted Selection to Develop a Drought-Tolerant Rice Line with Enhanced Resistance to Blast and Brown Planthopper

Rice is a major global staple crop, but rising temperatures and freshwater shortages have made drought one of the most severe abiotic stresses affecting agriculture. Additionally, rice blast disease and brown planthopper infestations significantly impact yields. Therefore, developing water-saving, drought-resistant, high-yielding, and disease-resistant rice varieties is critical for sustainable rice production. The new water-saving and drought-resistant (WDR) rice ‘Huhan 1516’, bred using marker-assisted selection (MAS) and marker-assisted backcrossing (MABC) techniques, addresses these challenges. This variety is highly adaptable to drought-prone and water-scarce regions such as the Yangtze and Huai River basins. With its high yield, drought tolerance, and broad-spectrum resistance to rice blast (conferred by the Pi2 gene) and brown planthopper (BPH), ‘Huhan 1516’ is suitable for various farming systems and environments. Field trials show that this variety outperforms control varieties by 2.2% in yield and exhibits moderate resistance to both rice blast and brown planthopper. ‘Huhan 1516’ has been recognized as a new water-saving and drought-resistant rice variety by the state, and as a released cultivar, it has great potential for market promotion and application.

Genome-wide identification of shaker K+ channel gene family in sugar beet (Beta vulgaris L.) and function of BvSKOR in response to salt and drought stresses

Potassium (K+) is the most abundant cation in plants, which is absorbed by roots and distributed throughout the plants and within plant cells, and is involved in various cellular processes. Shaker K+ channel plays crucial roles in the absorption and distribution of K+ and in the response to abiotic stress in plants. Herein, a total of six shaker K+ channel genes, BvKAT1, BvKAT3, BvAKT1, BvAKT2, BvAKT5, and BvSKOR, were identified in the genome of sugar beet (Beta vulgaris L.). The coding domain sequences (CDS) of these genes ranged from 2232 to 2739bp, and protein lengths were varied from 743 to 912 aa. The shaker K+ channel genes contained hormone-related and light responsiveness cis-acting regulatory elements. The phylogenetic analysis showed that BvSKOR was highly conserved and contained six transmembrane structures. The expression patterns of BvSKOR under salt and osmotic stress were analyzed by qRT-PCR, and found that the expression level of BvSKOR under low concentration salt and osmotic stress at short period of treatment were significantly higher than that of the control group. The function of BvSKOR was further verified in tobacco (Nicotiana tabacum), and the results showed that under salt and osmotic stress, the roots of transgenic plants were significantly stronger than those of wild type (WT) plants, and the relative water content (RWC), chlorophyll, proline, soluble sugar, soluble proteins contents and antioxidant enzyme activity were significantly higher than those of WT plants. These results indicated that overexpression of BvSKOR can significantly enhance the salt and drought tolerance in transgenic tobacco plants. This study could provide theoretical support and genetic resources for genetic improvement of crops stress resistance.

Decoding eggplant fruit: Multi-omics profiling of caffeoyl-CoA-3-OMT expression

Eggplant (Solanum melongena L.) is a rich source of health-promoting phenolic acids, mainly chlorogenic acid (CGA), and trace elements. CGA has been shown to have antioxidant, anti-inflammatory, neuroprotective, cardioprotective, anticancer, and antidiabetic properties. The natural genome of eggplants contains essential genes for beneficial traits like drought tolerance, disease resistance, and high concentrations of medicinal substances. Transcriptomic analysis of eggplant overexpressing the hydroxycinnamoyl CoA quinate hydroxycinnamoyl transferase (HQT) gene revealed upregulation of 2165 genes, including three similar to HQT and cinnamate-4-hydroxylase (C4H). Sequence similarity analysis showed homology to caffeoyl-CoA O-methyltransferases, key enzymes in the phenylpropanoid pathway leading to CGA biosynthesis. Gene ontology and KEGG pathway analysis identified 5 highly upregulated glycosyltransferase family 43 genes (650.3-fold change). Glycosyltransferases like UDP-glucose:cinnamate glucosyltransferase and cinnamate-glucose 4′-O-glucosyltransferase are crucial for CGA production in eggplant. qRT-PCR validated the potential upregulation of HQT and C4H in transgenic eggplants. Comparative analysis revealed eggplant has the highest CGA content (5–8.1 g/kg dry weight) among vegetables, with foliar CGA acting as a natural insecticide. CGA offers antioxidant, hypoglycemic, antiviral, and hepatoprotective benefits to humans. This study highlights the role of HQT and C4H in elevating the medicinal properties of eggplant through CGA biosynthesis pathway engineering.

Coupling of leaf economic and hydraulic strategy spectra facilitates desert restoration: A 70-year chronosequence study of Korshinks peashrub (Caragana korshinskii)

Vegetation restoration is a pivotal component in the restoration and management of desert. But shifts in the ecological strategies of established plant species, and how that may impact desert restoration, are both largely unknown. Here, we studied changes to the leaf economic strategy spectra (ESS), hydraulic strategy spectra (HSS) and soil strategy spectra (SSS) of the legume Caragana korshinskii in 3-, 5-, 10-, 20-, 30-, 40-, 50-, 60-, and 70-year restoration in Baijitan area of the MuUs desert, and investigated the relationship of these spectrums for enhancing desert restoration. The results showed that, over the years, both spectra changed significantly. The economic strategy of this plant shifted from a ‘fast investment-return’ to a more conservative ‘slow investment-return’ strategy. Concurrently, its hydraulic strategy transitioned from an isohydric to an anisohydric behavior. Along the restoration chronosequence, the resource acquisition strategy spectra declined in its effect and importance while the carbon investment in leaf construction increased. In this way, the drought tolerance and embolic resistance of plants were enhanced over time. We identify a coupling relationship between the economic and hydraulic strategy spectra. Furthermore, changed in the ESS and HSS influence the SSS over restoration years, ultimately favoring ecological restoration. This research provides foundational data for optimizing the cultivation management of Caragana korshinskii in terms of restoration years, enhancing ecosystem stability and productivity, and protecting and restoring the ecological environment.

Systematical characterization of Rab7 gene family in Gossypium and potential functions of GhRab7B3-A gene in drought tolerance

BackgroundCotton serves as a primary source of natural fibers crucial for the textile industry. However, environmental elements such as drought have posed challenges to cotton cultivation, resulting in adverse impacts on both production and fiber quality. Improving cotton’s resilience to drought could mitigate yield losses and foster the expansion of cotton farming. Rab7 protein, widely present in organisms, controls the degradation and recycling of cargo, and has a potential role in biotic and abiotic tolerance. However, comprehensive exploration of the Rab7 gene family in Gossypium remains scarce.ResultsHerein, we identified a total of 10, 10, 20, and 20 Rab7 genes through genome-wide analysis in Gossypium arboreum, Gossypium raimondii, Gossypium hirsutum, and Gossypium barbadense, respectively. Collinearity analysis unveiled the pivotal role of whole genome or segmental duplication events in the expansion of GhRab7s. Study of gene architecture, conserved protein motifs, and domains suggested the conservation of structure and function throughout evolution. Exploration of cis-regulatory elements revealed the responsiveness of GhRab7 genes to abiotic stress, corroborated by transcriptome analysis under diverse environmental stresses. Notably, the greatly induced expression of GhRab7B3-A under drought treatment prompted us to investigate its function through virus-induced gene silencing (VIGS) assays. Silencing GhRab7B3-A led to exacerbated dehydration and wilting compared with the control. Additionally, inhibition of stomatal closure, antioxidant enzyme activities and expression patterns of genes responsive to abiotic stress were observed in GhRab7B3-A silenced plants.ConclusionsThis study sheds light on Rab7 members in cotton, identifies a gene linked to drought stress, and paves the way for additional investigation of Rab7 genes associated with drought stress tolerance.

Investigating the Effects of Azadirachta Indica Leaf Extract on Drought Tolerance and Productivity of Mung Bean

Investigating the Effects of Azadirachta Indica Leaf Extract on Drought Tolerance and Productivity of Mung Bean

Effects of Straw Returning on Drought Tolerance and Growth Status of Maize Under Drought Stress in the Cold and Arid Regions of Northern China

Effects of Straw Returning on Drought Tolerance and Growth Status of Maize Under Drought Stress in the Cold and Arid Regions of Northern China

Evaluating the role of biopriming and nanopriming on the morphometric, biochemical, and yield parameters of Chickpea (Cicer arietinum L.) under drought stress

Evaluating the role of biopriming and nanopriming on the morphometric, biochemical, and yield parameters of Chickpea (Cicer arietinum L.) under drought stress

Integrating Solar Induced Fluorescence with High Throughput Plant Screening for Advanced Phenotyping of plants

There is an urgent need to address the escalating impacts of climate change, particularly the exacerbation of drought conditions, which pose significant threats to global food security and agricultural sustainability. Innovative solutions are imperative, and one such solution involves integrating advanced technologies like the "PlantArray" system to monitor and enhance plant physiological responses to water scarcity. The "PlantArray" system enables the precise measurement of critical whole-plant physiological traits such as transpiration rate, canopy stomatal conductance (Gs canopy), and growth rate with an exceptional spatiotemporal resolution. Augmenting this system with photosynthesis measurements offers an additional layer of information, facilitating a more focused interpretation of the system parameters. To overcome the limitations of single-leaf photosynthesis measurement techniques, this study employs a remote sensing approach to rapidly scan numerous samples at multiple time points, revealing insights into drought stress responses of S. licopersicum lines. An ultra-spectral spectroradiometer mounted on a mobile cart was positioned above an experimental matrix comprising drought-stressed S. licopersicum obsolete and mutagenic lines. Our findings reveal that the vegetation index PRI exhibited greater sensitivity to drought stress compared to other vegetation and photosynthesis remote sensing indices. Photosynthesis indices demonstrated increased sensitivity to daily biomass accumulation and served as predictors of final plant yield. Interestingly, Solar-Induced Fluorescence (SIF) parameters, solely indicative of photosynthesis-emitted fluorescence, exhibited no correlation with stress levels or final biomass production. This study articulates the potential to monitor plant responses to agricultural stressors through real-time physiological tracking across complete diel cycles, thereby enriching our understanding of plant-environment interactions. Ultimately, this integrated system shows promise in screening and developing crop cultivars with ideal physiological and photosynthetic traits, vital to cultivating resilient crops in extreme droughts and weather conditions.

An integrated transcriptome and physiological analysis of nitrogen use efficiency in rice (Oryza sativa L. ssp. indica) under drought stress

An integrated transcriptome and physiological analysis of nitrogen use efficiency in rice (Oryza sativa L. ssp. indica) under drought stress

Agronomic adaptations to heat stress: Sowing summer crops earlier

CONTEXTSummer crops are exposed to heat and drought stresses at critical stages during and after flowering, and their intensity and frequency are likely to increase with climate change. Agronomic stress avoidance offers the opportunity to temporally separate critical crop stages from heat and drought events. However, it might require sowing cold-sensitive summer crops earlier into colder than recommended soil temperatures. There is a need to understand how cold is too cold to sow summer crops early in late winter as well as what are the yield benefits and risks. OBJECTIVEHere, we quantify the likely benefits and trade-offs of sowing sorghum, a summer cereal, earlier to adapt to the increased frequency and intensity of heat and water stresses during flowering and grain filling. METHODSTwo years of multi-environment (n=32) genotype by management trials were conducted across the main sorghum growing regions of Australia. Environments (E) consisted of the combination of years, sites, three times of sowing (early, spring, and summer), and the use of supplementary irrigation. At each E a factorial combination of four plant populations (M) and eight commercial sorghum hybrids (G) were sown with three replications. Crop growth and yield components were measured, and the APSIM model was used to simulate all trials and treatments to quantify risks and derive insights into functional relationships between simulated and measured environmental covariates, and measured crop traits. RESULTSThe tested hybrids showed small differences in cold tolerance during crop establishment. Across the tested environments, the G×M combinations produced up to 60% variation in treatment yields across environment yields, which varied between <0.5 to about 10t ha-1; this translated into a ~5.5-fold variation in water use efficiency. Significant G×E and M×E interactions were observed for grain yield components. No G×M or G×E×M interactions were observed on yield or yield components. Early sowing was associated with a reduced risk of heat stress and water use transfer from vegetative to reproductive stages. Early sowing in late winter or early spring resulted in no significant yield gain or loss when all sites and years were included in the analysis. However, early sowing yielded between 1-2 t ha-1 more when the hottest sites and years were considered separately. This resulted from both the avoidance of heat stresses and milder or no terminal drought stresses. CONCLUSIONSEarly sowing of sorghum can reduce the likelihood of heat stresses around flowering as well as the likelihood of terminal drought stresses. Advantages include reduced yield losses in the hottest years and a transfer of water use to grain filling stages, resulting in increased grain yield and improved grain quality parameters. IMPLICATIONSEarly sowing, an agronomic adaptation, offers the opportunity to quickly adapt to the increase in the frequency and intensity of extreme hot events during critical crop stages. However, for the practice to be de-risked, there is a need to increase cold and chilling tolerance in sorghum and/or identify interventions that enhance seed germination and seedling vigour when the crop is sown early into cold soils.

Drought-mediated oxidative stress and its scavenging differ between citrus hybrids with medium and late fruit maturation

Drought stress is a major environmental factor limiting citrus productivity. Still, differences in drought sensitivity between citrus hybrids of different maturation periods have so far not been reported. Here, we selected a medium-maturing (Fertile orange: FO (Citrus reticulata cv. Fertile orange) and a late-maturing citrus hybrid (Newhall Navel orange: NO (Citrus sinensis Osbeck cv. Newhall) and determined the physiological and biochemical traits of leaves, roots, wood and bark. Our results showed that drought significantly decreased net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of citrus leaves. Oxidative stress upon drought was indicated by enhanced foliar malondialdehyde (MDA) and hydrogen peroxide contents, as well as a stimulation of the anti-oxidative system. This stimulation included the contents of dehydroascorbic acid (DHA), glutathione (GSH) and oxidized glutathione (GSSG) in leaves, roots, wood and bark, as well as activities of antioxidative enzymes of glutathione reductase (GR), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD) and peroxidase (POD). The late maturing NO hybrid not only showed better general physiological performance as indicated by increased Pn in leaves, but also higher biochemical ROS scavenging and osmotic capacity as indicated by increased ascorbic acids (ASA), DHA, and proline contents, as well as activities of enzymes of SOD, POD, ASA/DHA and GSH/GSSG ratios in the investigated tissues compared to the FO hybrid under drought and control conditions. Analysis of molecular mechanisms of signaling, regulatory and functional genes expression are suggested for future studies to elucidate the complex interplay of molecular, biochemical and physiological responses of citrus hybrids to drought.

Metabolomic and transcriptomic analyses reveal MYB-Related genes involved in drought resistance in grafted potatoes via the flavonoid pathway

Metabolomic and transcriptomic analyses reveal MYB-Related genes involved in drought resistance in grafted potatoes via the flavonoid pathway

Metarhizium anisopliae seed priming alleviates drought-induced oxidative stress and improves growth of barley (Hordeum vulgare L.)

Increasing crop resilience to drought stress through microorganisms is a sustainable approach. This study evaluated the efficacy of the endophytic fungus Metarhizium anisopliae MetA1 (MA) for improving drought tolerance of barley by analyzing various morphological, physiological, biochemical, and yield factors. Barley grains were treated with MA (1 × 108 spore/ml) and a pot experiment was conducted with three high-yielding barley genotypes: BARI Barley-10, BARI Barley-6, and BARI Barley-9 under three drought conditions: no drought (100% field capacity, FC), moderate drought (50% FC), and severe drought (25% FC). Under drought conditions, MA priming significantly enhanced shoot and root biomass, leaf characteristics, photosynthetic pigment content, and activities of various antioxidant enzymes including superoxide dismutase, catalase, glutathione S-transferase, ascorbate peroxidase, peroxidase, glutathione peroxidase, glutathione reductase, dehydroascorbate reductase, monodehydroascorbate reductase, glyoxalase-I, and glyoxalase-II in all barley genotypes. Furthermore, there was an observed increase in the levels of non-enzymatic antioxidants such as ascorbate and glutathione. MA treatment also led to a significant reduction in stress markers like methylglyoxal, malondialdehyde, lipoxygenase, hydrogen peroxide, and calcium influx along with an increase in proline and potassium content in barley leaves in stressed conditions. Crop growth and yield related attributes in barley were improved, which is evidence of better physiological and biochemical changes under both stress and non-stressed conditions. As such, the study provides evidence suggesting that MA-mediated seed priming is an effective strategy for improving drought tolerance not only in barley but also possibly other crops.

Evaluating stress tolerance indices for their comparative validity to access terminal heat stress and heat drought tolerance of winter wheat (Triticum aestivum L.) genotypes

Evaluating stress tolerance indices for their comparative validity to access terminal heat stress and heat drought tolerance of winter wheat (Triticum aestivum L.) genotypes

Effect of In Vitro Pretreatment with Ag-Containing Amino Acid Nanofibers on Biometrics and Antioxidant Activity in Drought-Stressed Ex Vitro-Adapted Stevia rebaudiana Bertoni

Biotechnological methods prevent the destruction of natural populations of medicinal plants due to climate change and developing agriculture. This study evaluates the effects of in vitro pretreatment with two types of silver-containing amino acid nanofibers (NF-1%Ag and NF1-Ag salt) on the drought tolerance of ex vitro soil-adapted Steviia rebaudiana Bertoni. The duration of the drought was five days. The data suggested that the pretreatment with the studied nanofibers during plant propagation enhanced the plant tolerance to drought stress manifested in a smaller decrease in plant biomass accumulation and a smaller increase in sugar content. The pretreatment with the two tested nanoparticles of well-watered plants increased the leaf fresh biomass accumulation of the ex vitro-adapted S. rebaudiana compared to the untreated WW control plants. The highest values were reported at 10 mg L−1 NF1-Ag salt. Five days of drought led to a decrease in the leaf fresh biomass compared to the WW plants, with the recorded lowest reduction again at 10 mg L−1 NF1-Ag salt. These observations correlate with antioxidant activity improvement. The results show that adding 10 mg L−1 NF1-Ag salt to the MS medium led to higher ex vitro-adapted S. rebaudiana resistance to water deficit than 100 mg L−1. This paper discusses the impact of the selected nanofibers on parameters characterizing plant growth and antioxidant activity of drought-stressed ex vitro-adapted Stevia rebaudiana plants.

Epigenomic studies in sorghum reveal differential enrichment of multiple histone marks at clade A PP2C genes in response to drought

Epigenetic regulation is essential for plant development and stress responses, as numerous stress-responsive genes are modulated epigenetically. However, most research has focused on individual histone marks. This study expands on previous work by examining the genome-wide profiles of seven histone marks (H3K9ac, H3K27ac, H3K4me3, H3K36me3, H3K27me3, H2A.Z, and H3K4me2) in sorghum leaves and roots under PEG-induced drought stress. Results revealed that five histone marks (excluding H3K36me3 and H3K27me3) were significantly associated with drought-responsive gene expression. The differential enrichment of these marks may enhance the induction of drought-responsive genes. Specifically, a subset of genes showed multiple histone marks' differential enrichment, with most clade A PP2C genes exhibiting enrichment for four marks after PEG treatment. This suggests a critical role for robust PP2C gene induction in sorghum’s drought response. Additionally, promoter cis-element analysis identified ERF family transcription factors as potential mediators of histone mark enrichment under drought conditions, providing new insights into the interaction between epigenetic modifications and transcriptional regulation in plant stress responses.