Improved Drought Tolerance Research Articles

Expression of Agrobacterium Isopentenyl transferase (IPT) gene in wheat improves drought tolerance.

Drought, as an abiotic stressor, globally limits cereal productivity, leading to early aging of leaves and lower yields. The expression of the isopentenyl transferase (IPT) gene, which is involved in cytokinin (CK) biosynthesis, can delay drought-induced leaf senescence. In this study, the Agrobacterium Isopentenyl transferase (IPT) gene was introduced into two local hexaploid wheat cultivars, NR-421 and FSD-2008. The expression cassette was developed containingthe IPT gene under transcriptional regulation of the stress-inducible promoter 'Dehydrin,' sourced from Hordeum vulgare. The gene expression cassette was assembled in pSB219M, a modified transformation vector for monocots, equipped with both an antibiotic (spectinomycin) and an herbicide selection marker (BASTA). Initial screening of transgenic plants involved BASTA selection (2 and 3mg/L) and was subsequently confirmed through PCR analysis. The transformation efficiencies of NR-421 and FSD-2008 were 0.4% and 0.3%, respectively. The qRT-PCR analysis under stress conditions showed a 13.5-fold higher expression of the IPT gene in T2 transgenic plants of NR-421 and a 5.8-fold higher expression in those of FSD-2008 than in non-transgenic controls. Under stress conditions, the wheat transgenic plants exhibited increased chlorophyll and relative water content. Additionally, for total soluble proteins, two transgenic lines from the NR-421 variety showed a significant increase, whereas no notable change was observed in the FSD-2008 transgenics. Moreover, the transgenic lines displayed increased plant height, higher fresh and dry biomass, and increased seed weight compared to the non-transgenic controls. These findings highlight that stress-inducible expression of the IPT gene in wheat leads to enhanced grain yield and subsequently improved drought tolerance.

MiR166e/ZmATHB14 module contributes to drought tolerance in maize root.

MicroRNAs significantly influence abiotic stress responses. A species-conserved miRNA implicated in the response to abiotic stress is maize miR166. Therefore, it is unknown whether miR166e plays a role in maize roots' reaction to drought stress. According to this study, drought stress lowers the expression of the miR166e precursor. According to genetic data, miR166e knockdown (KO) improved drought tolerance, while miR166e overexpression decreased it. Additionally, 5'-RACE and double luciferase tests have identified ZmATHB14, an HD-Zip III transcription factor, as a target of miR166e. Under drought stress, KO-miR166e alters ZmATHB14 expression and exhibits the opposite properties of miR166e. ZmATHB14 positively regulates the tolerance to drought stress. Furthermore, ZmATHB14, linked to the GTAATGATTAC cis-element, can activate transcription within the nucleus. Under drought stress, miR166e and ZmATHB14 contribute to vascular development and control ROS homeostasis. We discovered through metabolic targeting tests (Liquid chromatography-mass spectrometry, HPLC-MS) that ZmATHB14 modifies signaling pathways and hormone levels. Our findings strongly imply that the miR166e-ZmATHB14 module regulates drought tolerance.

Expression of spider silk protein in tobacco improves drought tolerance with minimal effects on its mechanotype.

Spider silk, especially dragline silk from golden silk spiders (Trichonephila clavipes), is an excellent natural material with remarkable mechanical properties. Many studies have focused on the use of plants as biofactories for the production of recombinant spider silk. However, the effects of this material on the mechanical properties or physiology of transgenic plants remain poorly understood. Since glycine-rich proteins play key roles in plants, we evaluated the effects of a glycine-rich spider silk protein on plant mechanical properties (mechanotype) and physiology. We generated tobacco (Nicotiana tabacum) plants producing a nucleus- or plastid-encoded partial component of dragline silk, MaSp1 (major ampullate spidroin-1; MaSp1-tobacco), containing six repetitive glycine-rich and polyalanine tandem domains. MaSp1 accumulation had minimal effect on leaf mechanical properties, but improved drought tolerance. Transcriptome analysis of drought-stressed MaSp1-tobacco revealed the upregulation of genes involved in stress response, antioxidant activity, cellular metabolism and homeostasis, and phenylpropanoid biosynthesis. The effects of drought treatment differed between the nucleus- and the plastid-encoded MaSp1-tobacco, with the latter showing a stronger transcriptomic response and a higher total antioxidant status (TAS). Well-watered MaSp1-tobacco displayed elevated levels of the stress phytohormone ABA, leading to stomatal closure, reduced water loss, activation of stress response, and increased TAS. We show that the moderately enhanced ABA content in these plants plays a pivotal role in drought tolerance, alongside, ABA priming, which causes overall adjustments in multiple drought tolerance mechanisms. Thus, our findings highlight the potential of utilizing glycine-rich spider silk proteins to enhance plant resilience to drought.

GhWRKY207 improves drought tolerance through promoting the expression of GhCSD3 and GhFSD2 in Gossypium hirsutum

GhWRKY207 improves drought tolerance through promoting the expression of GhCSD3 and GhFSD2 in Gossypium hirsutum

IMPROVING CROP DROUGHT TOLERANCE THROUGH GENOME EDITING TECHNOLOGY

The increase in the frequency and intensity of drought due to recent climate changes significantly affects agriculture. Addressing this challenge requires concerted research efforts to develop new crop varieties with increased tolerance to this abiotic stress. Genome editing technology is the latest approach in this direction. This review summarizes recent applications of genome editing in improving drought tolerance in various crops. The CRISPR/Cas9 technique is the newest and most advanced genome editing tool that gives exceptional versatility to develop improved varieties, thus facilitating their cultivation in drought conditions without compromising production.

Identification of ZmSNAC06, a Maize NAC Family Transcription Factor with Multiple Transcripts Conferring Drought Tolerance in Arabidopsis

Drought is one of the most serious environmental stresses affecting crop production. NAC transcription factors play a crucial role in responding to various abiotic stresses in plants. Here, we identified a maize NAC transcription factor, ZmSNAC06, between drought-tolerant and drought-sensitive inbred lines through RNA-seq analysis and characterized its function in Arabidopsis. ZmSNAC06 had five transcripts, of which ZmSNAC06-T02 had a typical NAC domain, while ZmSNAC06-P02 was localized in the nucleus of maize protoplasts and had transactivation activity in yeasts. The expression of ZmSNAC06 in maize was induced by drought. The overexpression of ZmSNAC06-T02 in Arabidopsis resulted in hypersensitivity to abscisic acid (ABA) at the germination stage, and overexpression lines exhibited higher survival rates and higher antioxidant enzyme activities compared with the wild-type under drought stress. These results suggest that ZmSNAC06 acts as a positive regulator in drought tolerance and may be used to improve drought tolerance in crops.

Exploring Drought Resistance Genes from the Roots of the Wheat Cultivar Yunhan1818.

The root is an important organ by which plants directly sense variation in soil moisture. The discovery of drought stress-responsive genes in roots is very important for the improvement of drought tolerance in wheat varieties via molecular approaches. In this study, transcriptome sequencing was conducted on the roots of drought-tolerant wheat cultivar YH1818 seedlings at 0, 2, and 7 days after treatment (DAT). Based on a weighted gene correlation network analysis of differentially expressed genes (DEGs), 14 coexpression modules were identified, of which five modules comprising 3107 DEGs were related to 2 or 7 DAT under drought stress conditions. A total of 223,357 single-nucleotide polymorphisms (SNPs) of these DEGs were retrieved from public databases. Using the R language package and GAPIT program, association analysis was performed between the 223,357 SNPs and the drought tolerance coefficient (DTC) values of six drought resistance-related traits in 114 wheat germplasms. The results revealed that 18 high-confidence SNPs of 10 DEGs, including TaPK, TaRFP, TaMCO, TaPOD, TaC3H-ZF, TaGRP, TaDHODH, TaPPDK, TaLectin, and TaARF7-A, were associated with drought tolerance. The RT-qPCR results confirmed that these genes were significantly upregulated by drought stress at 7 DAT. Among them, TaARF7-A contained three DTC-related SNPs, which presented two haplotypes in the tested wheat germplasms. YH1818 belongs to the Hap1 allele, which is involved in increased drought tolerance. This study revealed key modules and candidate genes for understanding the drought-stress response mechanism in wheat roots.

Role of exopolysacharide bacteria in improving the tolerance of Zea mays (L.) Seedlings to drought stress

In this study, 20 Bacillus and 20 Pseudomonas bacteria were isolated from arid and semiarid soil samples. Bacillus and Pseudomonas bacteria are soil-dwelling bacteria that can promote plant growth. They are known to produce exopolysaccharides (EPS), which can help plants retain water and tolerate drought stress. The isolates were morphologically and microscopically characterized and tested for their ability to produce exopolysaccharides. The isolates that were most capable of producing exopolysaccharides were used as biofertilizer to improve drought tolerance of maize seedlings. The seedlings were irrigated every 24, 48, or 72 h. The results showed that biofertilizers containing the most EPS-producing Bacillus and Pseudomonas isolates, B. subtillus, B. brevibacillus, P. putida, P. fluorescens, significantly improved the transpiration rate, stress tolerance index, drought tolerance, chlorophyll stability and membrane damage index of maize seedlings.

Identification of crucial drought-tolerant genes of barley through comparative transcriptomic analysis and yeast-based stress assay

Drought is a persistent and serious threat to crop yield and quality. The identification and functional characterization of drought tolerance-related genes is thus vital for efforts to support the genetic improvement of drought-tolerant crops. Barley is highly adaptable and renowned for its robust stress resistance, making it an ideal subject for efforts to explore genes related to drought tolerance. In this study, two barley materials with different drought tolerance were subjected to soil drought treatment, including a variety with strong drought tolerance (Hindmarsh) and a genotype with weaker drought tolerance (XZ5). Transcriptomic sequencing data from the aboveground parts of these plants led to the identification of 1,206 differentially expressed genes associated with drought tolerance. These genes were upregulated in Hindmarsh following drought stress exposure but downregulated or unchanged in XZ5 under these same conditions, or were unchanged in Hindmarsh but downregulated in XZ5. Pathway enrichment analyses suggested that these genes are most closely associated with defense responses, signal recognition, photosynthesis, and the biosynthesis of various secondary metabolites. Using protein-protein interaction networks, the ankyrin repeat domain-containing protein 17-like isoform X2 was predicted to impact other drought tolerance-related protein targets in Hindmarsh. In MapMan metabolic pathway analyses, genes found to be associated with the maintenance of drought tolerance in Hindmarsh under adverse conditions were predicted to include genes involved in the abscisic acid, cytokinin, and gibberellin phytohormone signaling pathways, genes associated with redox homeostasis related to ascorbate and glutathione S-transferase, transporters including ABC and AAAP, transcription factors such as AP2/ERF and bHLH, the heat shock proteins HSP60 and HSP70, and the sucrose non-fermenting-1-related protein kinase. Heterologous HvSnRK2 (one of the identified genes, which encodes the sucrose non-fermenting-1-related protein kinase) gene expression in yeast conferred significant drought tolerance, highlighting the functional importance of this gene as one linked with drought tolerance. This study revealed the drought tolerance mechanism of Hindmarsh by comparing transcriptomes while also providing a set of candidate genes for genetic efforts to improve drought tolerance in this and other crop species.

Rhizophagus irregularis regulates RiCPSI and RiCARI expression to influence plant drought tolerance.

Arbuscular mycorrhizal fungi (AMF) can transfer inorganic nitrogen (N) from the soil to host plants to cope with drought stress, with arginine synthesis and NH4+ transport being pivotal processes. However, the regulatory mechanism underlying these processes remains unclear. Here, we found that drought stress upregulated expression of genes involved in the N transfer pathway and putrescine and glutathione synthesis in the mycorrhizal structures of Rhizophagus irregularis within alfalfa (Medicago sativa) roots, i.e., carbamoyl-phosphate synthase (RiCPSI), arginase (RiCARI), urease (RiURE), ornithine decarboxylase (RiODC), and glutamate-cysteine ligase (RiGCL). Furthermore, we confirmed that RiCPSI is a carbamoyl phosphate synthase. Silencing RiCARI via host-induced gene silencing inhibited arbuscule formation, suppressed putrescine and glutathione synthesis, and altered arginine metabolism within R. irregularis-plant symbiosis, leading to a substantial reduction in the drought tolerance of M. sativa. Conversely, silencing RiCPSI decreased arginine, putrescine, and glutathione synthesis in R. irregularis but did not adversely affect NH4+ transfer from fungi to the host plant and drought tolerance of M. sativa. Interestingly, overexpressing RiCPSI via our host-induced gene overexpressing system enhanced arginine, putrescine, and glutathione synthesis in R. irregularis, reduced arbuscule abundance, and improved drought tolerance of M. sativa. Our findings demonstrate that, under drought stress, R. irregularis-plant symbiosis facilitates improved NH4+ transfer from AMF to the host plant. This is accompanied by increased arginine, putrescine, and glutathione synthesis within R. irregularis, driven by the upregulation of RiCPSI and RiCARI expression in mycorrhizal structures within the roots. These molecular adjustments collectively contribute to enhanced drought tolerance in R. irregularis-plant symbiosis.

Genome-wide association study on root traits under non-stress and osmotic stress conditions to improve drought tolerance in rice (Oryza sativa Lin.)

Genome-wide association study on root traits under non-stress and osmotic stress conditions to improve drought tolerance in rice (Oryza sativa Lin.)

Arbuscular Mycorrhiza Fungi's Effects on Gt 1 Hevea brasiliensis Seedlings' Growth and Physiological Performance in a Drought-Stressed Environment

Drought significantly affects rubber (Hevea brasiliensis Muell. Arg.) cultivation, especially in marginal regions with limited rainfall. This study investigates the potential benefits of arbuscular mycorrhizal fungi (AMF) inoculation on GT 1 rubber seedlings' growth and physiology under drought stress. Topsoil samples were collected and either sterilised or left non-sterilised. AMF inocula were prepared, and GT 1 rubber seedlings were transplanted into bags with different soil types and subjected to watering or drought. Growth parameters and water deficit were measured and analysed. Growth parameters revealed complex interactions between soil type, AMF inoculation, and watering regimes. Well-watered seedlings generally outperformed drought-stressed ones, but certain AMF treatments showed higher stem height. Percentage growth in girth size and height varied among treatments, emphasising the influence of AMF and drought. Leaf area measurements indicated the positive effect of AMF on physiological performance. Results showed the highest girth size at 30 WAT with NS/C/W (0.61 cm). Significant differences in seedling height were observed, with AMF-OP9 in the watered regimen having the highest stem height (62.25 cm at 30 WAT). The highest percentage increase in girth size at 30 WAT was noted in the S/GD/D treatment combination (64.29%). The highest percentage increase in height was in the NS/N4/D treatment combination (20.90 cm at 30 WAT). AMF inoculation enhanced seedling growth, but the response depended on specific conditions. Drought stress negatively impacted growth and water status, with AMF-OP9 demonstrating potential drought tolerance. Water potential and relative water content varied with AMF treatments, soil types, and watering regimes. AMF-OP9 showed promise in improving drought tolerance and water retention. This study highlights AMF's potential to enhance GT 1 rubber seedling growth and physiology in drought-prone regions. Understanding the context-dependent effects of AMF is crucial for optimizing rubber tree cultivation. Further research is needed to elucidate AMF-mediated drought tolerance mechanisms.

Improvement of maize drought tolerance by foliar application of zinc selenide quantum dots.

Maize (Zea mays L.) is an important cereal crop grown in arid and semiarid regions of the world. During the reproductive phase, it is more frequently exposed to drought stress, resulting in lower grain yield due to oxidative damage. Selenium and zinc oxide nanoparticles possess inherent antioxidant properties that can alleviate drought-induced oxidative stress by the catalytic scavenging of reactive oxygen species, thereby protecting maize photosynthesis and grain yield. However, the effect of zinc selenide quantum dots (ZnSe QDs) under drought stress was not been quantified. Hence, the aim of this study was to quantify the (i) toxicity potential of ZnSe QDs and (ii) drought mitigation potential of ZnSe QDs by assessing the transpiration rate, photosynthetic rate, oxidant production, antioxidant enzyme activity and seed yield of maize under limited soil moisture levels. Toxicity experiments were carried out with 0 mg L-1 to 500 mg L-1 of ZnSe QDs on earthworms and azolla. The results showed that up to 20 mg L-1, the growth rates of earthworms and azolla were not affected. The dry-down experiment was conducted with three treatments: foliar spray of (i) water, (ii) ZnSe QDs (20 mg L-1), and (iii) combined zinc sulfate (10 mg L-1) and sodium selenate (10 mg L-1). ZnSe or Se applications under drying soil reduced the transpiration rate compared to water spray by partially closing the stomata. ZnSe application at 20 mg L-1 at the tasselling stage significantly increased the photosynthetic rate (25%) by increasing catalase (98%) and peroxidase (85%) enzyme activity and decreased the hydrogen peroxide (23%) content compared to water spray, indicating that premature leaf senescence was delayed under rainfed conditions. ZnSe spray increased seed yield (26%) over water spray by increasing the number of seeds cob-1 (42%). The study concluded that foliar application of ZnSe (20 mg L-1) could decrease drought-induced effects in maize.

Analyses of the bHLH gene family in Populus trichocarpa reveal roles of four PtbHLHs in regulating the drought stress response

As one of the largest families of transcription factors in plants, the basic helix-loop-helix (bHLH) transcription factor family regulates a wide range of functions in plants. However, little is known about the functions of bHLH family members in Populus trichocarpa during plant growth and in the response to drought stress. In our study, 190 PtbHLH genes were identified in the P. trichocarpa genome and classified into 21 groups. Analyses of microarray datasets showed that most PtbHLH members not only have multiple functions in poplar growth, but also respond rapidly to drought stress in the leaves or roots. We selected four genes, PtbHLH35, PtbHLH121, PtbHLH137, and PtbHLH152, which were highly expressed in leaves or roots under drought stress, for functional validation analyses. These genes encoded nucleus-localized bHLH transcription factors. Transient expression of PtbHLH35, PtbHLH121, and PtbHLH152 in P. trichocarpa improved drought tolerance by activating the antioxidant system to eliminate reactive oxygen species and reduce the degree of cell damage in the leaves under drought stress. Overexpression of PtbHLH137 improved drought tolerance by activating antioxidant enzymes in the roots to eliminate reactive oxygen species, and by increasing the abscisic acid content in the roots in response to drought stress. Together, our findings provide insights into the functions of PtbHLH family members in growth and in the response to drought.

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.

Genome-wide identification of the bHLH transcription factor family and the regulatory roles of PbbHLH74 in response to drought stress in Phoebe bournei.

Phoebe species constitute a large portion of subtropical forestry, which are key players in biomass resources. However, abiotic stresses such as drought stress severely limit the growth and development of P. bournei, and even lead to its death. It has been shown that basic helix-loop-helix (bHLH) as the second largest transcription factor family plays essential roles in response to multiple stresses in plants. However, little information of bHLH family is available in P. bournei. In this study, 130 PbbHLHs were identified and classified into 24 subfamilies. Then, the bHLH domain, conserved motifs and gene structures, evolutionary patterns and protein structural features were probed. The expression levels of 17 PbbHLHs were differentially induced by PEG and ABA by RT-qPCR analysis, indicating that they may be involved in drought stress response. Characterization of the drought candidate gene PbbHLH74 showed that it was transcriptionally active and localized in the nucleus. Heterologous transformation of PbbHLH74 into yeast improved cellular tolerance to drought stress. Meanwhile, overexpression of PbbHLH74 in Arabidopsis showed higher seed germination, plant biomass and expression levels of stress-related genes under drought conditions. Through the hairy root technique, overexpression of PbbHLH74 in P. bournei improved drought tolerance by enhancing root development and expression levels of genes involved in ABA-dependent and ROS scavenging pathways. Moreover, PbbHLH74 might positively regulate the expression of PbPOD by Y1H and dual-luciferase reporter assays. Overall, these results elucidated the structure and evolution of the PbbHLH family, in which PbbHLH74 could be applied to molecular assisted breeding for drought tolerance in P. bournei.

A comparison of drought responses in wild wheat relatives and domesticated wheat grown under irrigated and rainfed field conditions

ContextDomestication and breeding processes for developing modern wheat plants from diverse wild relatives and landraces have had unintended effects of loss of genetic diversity. This reduction in genetic variation undermines the ability of modern wheat cultivars to tolerate environmental stresses such as drought. Wheat wild relatives possess untapped genetic potential for tolerating abiotic stress, especially drought. Yet, their morpho-physiological adaptation and drought stress resilience mechanisms remain underexplored. ObjectiveThis study aimed to investigate the adaptive responses of plants within the Triticum spp. genepool, encompassing wheat wild relatives, landraces, and modern cultivars to drought stress under rainfed and irrigated field conditions. MethodsFrom an initial pool of 110 genotypes screened during the first growing season in 2022, 20 best performing genotypes, including modern cultivars for comparison, were selected for a second growing season in 2023 based on their relative yield performance. Two different treatment conditions, irrigated and rainfed, were applied during both growing seasons. This experiment observed single plants per replicate. Multiple parameters, including days to heading and flowering, plant height, number of spikes per plant, spike length, spike weight per plant, straw weight per plant, aboveground biomass per plant, grain yield per plant, thousand kernel weight, harvest index, stomatal conductance, and vegetation indices, were assessed on the selected genotypes. ResultsTaking averages measured across both growing seasons, we observed significant genotypic variation across several parameters: days to heading and flowering, plant height, number of spikes per plant, spike length, spike and straw weight per plant, aboveground biomass per plant, grain yield per plant, thousand kernel weight, harvest index, stomatal conductance, and vegetation indices. Water stress during the rainfed treatment significantly reduced grain yield (by 21 %) and stomatal conductance (by 45 %). Stomatal conductance was associated with grain yield and yield-related traits under rainfed conditions. Diverse physiological drought tolerance mechanisms associated with stomatal regulation were identified, revealing genotype-specific responses to drought stress. Genotypes such as T. dicoccoides (G242), T. urartu (G45), T. boeoticum (G27) and T. araraticum (G221) exhibited isohydric adaptation, whereas T. monococcum sinskajae (G89) and T. durum cv. Sambadur (G41) exhibited anisohydric adaptation. ConclusionSome genotypes of T. dicoccoides, T. urartu, T. boeoticum and T. araraticum exhibited isohydric adaptation, while T. monococcum sinskajae and T. durum cv. Sambadur exhibited anisohydric adaptation under drought stress which needs further verification. These genotypes can serve as donors for introducing drought tolerance traits within wheat improvement programs. ImplicationsThese findings holds great significance in improving drought tolerance in modern wheat breeding programs.

Evaluating Drought Tolerance and Yield Stability of Sorghum Genotypes for Sustainable Agriculture in Sohag, Egypt

ABSTRACTThe major problem in the cultivation of sorghum in the Egyptian agricultural system includes arid climate and water shortage. Thus, the present study was undertaken to investigate the effect of drought conditions on the productivity of 21 different sorghum (Sorghum bicolor L.) genotypes at Sohag, Egypt. A set of drought tolerance metrics employed in the present study were Tolerance Index (TOL); Mean Production (MP); Sensitivity to Drought Index (SSI); Stress Tolerance Index (STI); Geometric mean performance (GMP) and Harmonic mean of yield (HARM). A field‐controlled experiment was conducted on the two growth seasons (2021 and 2022) concerning the impact of different drought levels on (ET0 = 0.8, 0.6 and 0.4) Grain Yields (GY) and Water Use Efficiency (WUE) for the various studied sorghum genotypes. Principal Component Analysis (PCA) was also conducted on the obtained data of the different yield parameters with the aim of identifying the most effective tolerance indices related to the different genotypes of sorghum under both conditions, optimal and stressed. Drought tolerance varies among different sorghum varieties, which, by their genetic and physiological nature, possess efficient stomatal regulation and deep‐rooted systems, enhancing water conservation and physiological functions and hence higher WUE. These are mainly influenced by environmental conditions, such as soil type and moisture levels in the region of Sohag, where such genotypes may exhibit different performances regarding drought stress. It was observed that Giza‐15 and Hybrid Sh1 were among the high performers under well‐irrigated conditions, and L38 was outstanding during a severe drought in terms of WUE. Therefore, proper genotype selection depends on the irrigation strategy. Hence, the Sohag region presents a good opportunity for further improvement of drought tolerance through designed selection and hybridization activities in sorghum breeders, and this contributes to climate‐resilient cultivars by addressing the present agricultural challenges and food security for the present world. Emphasis will be placed by breeders on the development of arid‐condition‐adapted genotypes and the development of models that can be applied within comparable climates to boost productivity and sustainability for those farmers dependent on this vital crop.

Advancing rice breeding for drought tolerance: a comprehensive study of traditional and mutant lines through agronomic performance and drought tolerance indices

BackgroundDrought stress is a critical challenge to rice production, necessitating the development of drought-tolerant genotypes. This study aimed to evaluate the drought tolerance of rice genotypes, including traditional parental lines (Hashemi, Khazar, Fajr, and Tarom Mahalli) and their corresponding mutant lines, under normal and drought stress conditions.MethodsAgronomic traits such as plant height, spike number, spike length, seed fertility, and yield were analyzed under both conditions. The performance of these genotypes was further assessed using drought tolerance indices. Statistical methods including cluster analysis and principal component analysis (PCA) were applied to identify the most resilient genotypes.ResultsMutant lines demonstrated superior drought resilience compared to their parental counterparts. Specifically, genotypes like TM-230-VE-7-5-1, TM-B-2-1-E, and HM-250-7-6 exhibited higher yields and better stability of key traits under stress conditions. Cluster analysis and PCA emphasized the strong performance of TM-230-VE-7-5-1, which emerged as the most drought-tolerant genotype, excelling across various drought tolerance indices.ConclusionsThe selected mutant lines, particularly TM-230-VE-7-5-1, showed significant potential for breeding programs aimed at improving drought tolerance in rice. These findings have substantial implications for enhancing rice production in drought-prone regions, contributing to sustainable agricultural practices.

Metabolite profiling in ten bread wheat (Triticum aestivum L.) genotypes in response to drought stress

Wheat is frequently constrained by extreme environmental conditions such as drought. Improving drought tolerance in wheat genotypes is crucial for ensuring food security, especially considering the challenges posed by climate change. To reveal the involvement of metabolites in drought response, ten diverse wheat genotypes were investigated under control and water scarcity conditions. The field experiments were set-up, using a 5 × 2 alpha lattice design, with two replicates per treatment, in the 2022 and 2023 growing seasons. Metabolites associated with drought tolerance were analysed using ultra-high performance liquid chromatography, coupled with a quadruple time of flight mass spectrometry (UHPLC-qTOF-MS). Multivariate statistical analysis (MVDA) tools, viz. principal component analysis (PCA) and the orthogonal projection to latent structures-discriminant analysis (OPLS-DA) loading scatter plot were used to identify the metabolites that are positively and negatively correlated to drought stress. Significant variation (p < 0.05) among genotypes was observed, with 58 metabolites annotated, including phenolic acids, carbohydrates, and fatty acids. The annotated compounds were linked to thirteen most significant pathways, with one carbon metabolism, cutin, suberin and wax synthesis and starch and sucrose metabolism being significantly affected by water stress, based on the KEGG pathway analysis. The two high-yielding wheat genotypes (LM48 and BW140) under drought stress displayed significant upregulation of key metabolites such as sinapoyl hydroxyagmatine, 7-oxostigmasterol, 1-O-caffeoyl-3-O-p-coumaroylglycerol, and 3-beta-3-lupanol, when compared to the non-stressed conditions. This study demonstrates the prospects of applied metabolomics for chemotaxonomic classification, phenotyping and selection in plant breeding, as well as potential use in crop improvement.