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Synthetic community derived from the root core microbes of a desert shrub Caragana korshinskii enhances wheat drought tolerance.

BACKGROUND: Drought, intensified by climate change, poses a mounting threat to global food security by severely constraining crop productivity. While microbial inoculants offer promise for drought tolerance, their poor adaptability remains insufficient for extremely water-deficient environments. Desert plants host unique drought-adapted microbiomes that remain largely unexplored for agricultural applications. RESULTS: Here, we investigated the microbial community of the desert shrub Caragana korshinskii and identified a core set of drought-responsive strains. A synthetic microbial community (SynCom) derived from these strains significantly improved wheat growth under drought stress. Metagenomic analyses revealed that microbial functions related to biofilm formation, quorum sensing, and carbon metabolism were enriched, with Pseudomonas identified as a key functional taxon. Guided by inter-strain interactions in biofilm assembly, we streamlined the consortium into a five-member synthetic community, where quorum-sensing signals promoted community-wide biofilm formation. Community biofilm production improved strain colonization and conferred greater drought tolerance compared to monocultures. In plants, mechanistic investigations indicated that the simplified SynCom inoculation universally upregulated MAPK and jasmonic acid signaling pathways. Furthermore, carbohydrate metabolic pathways such as starch and sucrose metabolism were specifically activated, suggesting a multi-level mechanism underlying SynCom-mediated drought tolerance. CONCLUSIONS: These findings demonstrate that SynCom constructed on the endophytic flora of desert plants can significantly enhance crop drought tolerance. Our work highlights the pivotal role of community biofilm synthesis in facilitating root colonization and activating a multidimensional drought tolerance network in plants. This study not only gives an ecological perspective on desert microbiome adaptations but also offers a strategic framework for developing effective microbial inoculants for arid-region agriculture. Video Abstract.

Caragana

Identifying canopy wilting QTLs and evaluating remote sensing approaches for selecting drought-tolerant soybean.

Drought is the most damaging abiotic stress for soybean yield; cultivars with improved drought tolerance are needed to sustain and increase crop production. PI 603535 previously was identified as an ultra-slow canopy wilting (CW) line in a genome-wide association study but the quantitative trait loci (QTLs) underlying this phenotype have not been determined. In this study, a recombinant inbred line (RIL) population derived from Benning × PI 603535 was evaluated for three years under rain-fed conditions. CW was rated following extended periods of drought when CW variation was present. Aerial multispectral and thermal imagery was also captured in conjunction with visual ratings to explore the feasibility of implementing remote sensing to improve the efficiency and objectivity of drought evaluations. The normalized difference vegetation index (NDVI) and green-based NDVI (GNDVI) exhibited strong, significant correlations (|r|= 0.42-0.44) with CW across years. CW scores and the remote sensing traits were used as phenotypes for QTL mapping. Seven CW QTLs were identified across six chromosomes in the combined analysis, with NDVI and GNDVI QTLs generally colocalizing with the CW QTLs with the highest percentage of variation explained (PVE). The QTLs were not consistently identified among individual years, highlighting the complex genetics and gene expression of drought tolerance. The instability and low additive effect estimates of individual QTLs imply challenges of improving drought tolerance through the selection of a few QTLs. However, the slow CW RILs developed in this study can serve as valuable breeding stocks for future drought improvement breeding efforts and genetic studies.

Quantitative Trait Loci

Transcriptional regulation reveals potent drought tolerance mechanisms in contrasting genotypes of Cajanus cajan (L.) Millspaugh.

Global warming severely impacts crop productivity, particularly in the Global South. Tropical pulse crops are nutritious staples and tolerant to harsh conditions, such as pigeonpea (Cajanus cajan). Two pigeonpea varieties have superior qualities, also with respect to abiotic stress tolerance: drought-tolerant Pusa Arhar 16 (PA16) and moderately drought-sensitive Pusa 992 (PA99). However, both are understudied at the molecular level. This study investigates molecular mechanisms of drought tolerance by investigating their responses to polyethylene glycol-induced drought. Superior drought tolerance in PA16 was characterized by enhanced shoot growth, photosynthetic characteristics and reduced oxidative stress as compared to PA992, while root length showed no significant difference between the varieties. Transcriptomic analysis identified differentially expressed genes among treatments and varieties, significantly upregulated under drought in PA16 versus PA992 with distinct patterns. For example, genes encoding terpenoid biosynthesis were up-regulated only in PA16, while those encoding LATE EMBRYOGENESIS ABUNDANT (LEA) proteins were drought-induced in both, PA16 and PA992. Functional enrichment analyses coupled with Weighted Correlation Network Analysis uncovered co-expression networks regulating drought-related pathways. Hence, the genotype and environment-specific gene regulation patterns suggest molecular and physiological mechanisms related to secondary metabolisms and LEA proteins underlying drought resilience in pigeonpea. This research offers potential targets for breeding drought-tolerant varieties of this important legume crop.

Cajanus

The TaCEP15 peptide signaling cascade modulates primary root length and drought tolerance in wheat.

Drought stress poses an environmental challenge affecting crop yield. Small signaling peptides play crucial roles in the regulation of stress responses in plants. Here, we unveil that the TaCEP15 peptide interacts with the leucine-rich repeat receptor-like kinase TaCEPRL. Knockout of TaCEP15 or TaCEPRL increases primary root length and enhances drought tolerance in wheat. TaCEPRL interacts with and phosphorylates TaSnRK1α, leading to the degradation of TaSnRK1α. The presence of TaCEP15 intensifies the phosphorylation and degradation of TaSnRK1α. Consistently, overexpressing TaSnRK1α boosts primary root elongation and augments drought tolerance. In addition, we identify the transcription factor TabZIP9, which binds to the TaCEP15 promoter and suppresses its transcription. A-to-T substitution in the TaCEP15 promoter decreases the binding affinity of TabZIP9. As expected, transgenic plants with TabZIP9 knockout or overexpression exhibit noteworthy changes in primary root length and drought tolerance. Our findings shed light on the importance of the peptide signaling pathway in regulating primary root length and responding to drought stress in wheat.

Triticum

Comparative transcriptomic and physiological analyses uncover key regulatory pathways associated with drought tolerance in wheat.

Drought severely limits wheat yield, yet its molecular basis remains incompletely understood. We compared a drought-tolerant line (A25) and a drought-sensitive line (A8) under water deficit across three developmental stages using physiological assays and transcriptomics. A25 exhibited stronger osmotic adjustment and antioxidant defense, with higher proline accumulation and enhanced activities of ascorbate peroxidase, catalase, and other ROS-scavenging enzymes. RNA-seq revealed distinct drought-responsive expression patterns, with differentially expressed genes enriched in MAPK signaling and ABA-dependent pathways. ABA-responsive genes were more abundant and strongly induced in A25, suggesting enhanced ABA signal transduction as a key mechanism. Weighted gene co-expression network analysis identified a drought-associated purple module positively correlated with physiological resistance, from which six hub genes (MAPKKK17, Avr9/Cf-9, RPPL1, RGA1, UBC28, AGPs5) were highlighted as potential regulators. Collectively, coordinated activation of ABA signaling and MAPK cascades, mediated by these hub genes, underlies the robust drought tolerance of A25, providing promising molecular targets for wheat breeding and improvement.

Triticum

Heterologous expression of DobHLH25 from Dendrobium officinale enhances drought tolerance in Arabidopsis.

Drought stress severely constrains the growth, yield, and accumulation of bioactive compounds in Dendrobium officinale (D. officinale), a valuable medicinal orchid, and this challenge is exacerbated under simulated wild cultivation where plants are inevitably exposed to recurring water deficits. Basic helix-loop-helix (bHLH) transcription factors are well-established regulators of plant abiotic stress responses. However, the molecular mechanisms by which bHLH transcription factors respond to drought stress in this species remain largely unknown. In this study, a bHLH transcription factor gene, DobHLH25, was cloned from D. officinale. Phylogenetic analysis revealed that DobHLH25 shares the highest sequence identity with its ortholog in Dendrobium nobile. Additionally, subcellular localization analysis indicated that DobHLH25 is targeted to the nucleus and possesses a functional transcriptional activation domain. Expression pattern analysis showed that DobHLH25 is most abundantly expressed in old leaves, and its expression in roots, stems, and leaves is induced by polyethylene glycol treatments. Heterologous expression of DobHLH25 in Arabidopsis thaliana resulted in higher seed germination rates and longer root lengths under mannitol-induced osmotic stress compared to wild-type plants. Under drought stress, DobHLH25 heterologous expression lines exhibited higher survival rates, reduced leaf water loss, lower malondialdehyde accumulation, and increased proline content. Moreover, the activities of antioxidant enzymes such as superoxide dismutase and peroxidase were significantly enhanced, and the expression levels of multiple drought-responsive genes were markedly upregulated. Collectively, these findings suggest a correlation between DobHLH25 expression and plant drought tolerance, as evidenced by reduced oxidative damage, increased osmolyte accumulation, enhanced antioxidant enzyme activities, and upregulation of drought-responsive genes. Together, these results suggest that DobHLH25 plays a positive role in drought tolerance, and provides a basis for future dissection of its regulatory network in D. officinale.

Drought Resistance

Clone and characterization of a cytochrome P450 gene for drought tolerance in rice.

BACKGROUND: Drought is a major abiotic stress limiting rice production worldwide. Identifying genes that enhance drought tolerance is essential for breeding resilient varieties. RESULTS: In this study, we report the map-based cloning and functional characterization of DT1, a novel cytochrome P450 gene conferring drought tolerance in rice. Using near isogenic lines (NILs) derived from a cross between Xiang743 and Katy, we delimited DT1 into a 115 kb interval on chromosome 3, where contains 18 open read frames (ORFs). Quantitative real-time polymerase chain reaction (qRT-PCR) analysis identified Os03g55250 as the candidate gene. Clustered regularly interspaced short palindromic repeats-associated nuclease 9 (CRISPR/Cas9) knockout mutants of Os03g55250 exhibited increased drought sensitivity, while overexpression lines showed enhanced drought tolerance, confirming that Os03g55250 was the target gene and positively regulates drought resistance. DT1 was mainly expressed in stems, leaves, and leaf sheaths, and the DT1 protein localized in the endoplasmic reticulum. Haplotype analysis identified Hap1 as a favorable allele in japonica rice. CONCLUSIONS: Our findings provide a promising genetic resource for breeding drought-resistant rice varieties and offers new insights into the role of P450 genes in abiotic stress adaptation.

Oryza

Discovery of specific rhizosphere bacteria Rhodanobacter involved in KAI2-mediated drought tolerance in Arabidopsis.

The KARRIKIN INSENSITIVE 2 (KAI2) receptor has been reported to contribute to drought tolerance in Arabidopsis. However, the extent to which KAI2's function in drought tolerance depends on soil microbiota remains unclear. This study demonstrates that the rhizosphere microbiome is indispensable for KAI2-mediated drought tolerance. We isolated specific Rhodanobacter sp. and confirmed its role in enhancing drought tolerance in Arabidopsis. Notably, Rhodanobacter sp. was found to specifically secrete the key isoflavone daidzin. We found that daidzin had a similar function with KAI2 agonist, desmethyl-type germinone, and induced interaction between KAI2 and SUPRESSOR OF MORE AXILLARY GROWTH 2 1. Moreover, the exogenous application of daidzin enhanced drought tolerance by modulating the expression of karrikin response and drought-related genes, in a KAI2-dependent manner. Our findings suggest that the rhizosphere microbiome plays a crucial role in facilitating KAI2-mediated drought tolerance in Arabidopsis, with Rhodanobacter sp. contributing through the secretion of daidzin.

Arabidopsis

Multi-Omics insights into OsZFP252-OsGA20ox5 mediated drought tolerance in rice through stomatal and vascular regulation.

Rice growth is highly dependent on water availability, and drought stress significantly impacts its entire life cycle. However, previous studies lack systematic investigations into drought-responsive candidate genes across the full life cycle of rice. This study integrates transcriptomic and phenotypic data from two rice lines, IR64 (drought-sensitive) and DK151 (drought-tolerant), under varied environmental conditions at distinct growth stages. Using k-means clustering, 13 369 genes were categorized into 17 distinct expression patterns, revealing drought-responsive genes specifically upregulated or downregulated under drought stress. Weighted co-expression network analysis (WGCNA) further identified four gene modules strongly correlated with drought-related phenotypes, co-localizing 2859 drought-responsive genes through both approaches. Proteomics and metabolomics were supplemented at the booting stage, where phenotypic and transcriptomic differences under drought were most pronounced. Integrated omics results demonstrate gibberellin (GA) and abscisic acid (ABA) pathways play a key role during drought tolerance in rice, and 79 high-confidence drought-resistant candidate genes were prioritized from the 2859 drought-responsive genes. Among these, Gibberellin 20-oxidase 5 (OsGA20ox5) was identified as a key negative regulator of drought tolerance. Furthermore, the transcription factor zinc finger protein 252 (OsZFP252) directly binds to the OsGA20ox5 promoter, repressing its expression and enhancing ABA biosynthesis, thereby improving drought tolerance by increasing stomatal closure and expanding vascular bundle water transport capacity. Notably, the drought-tolerant haplotype 2-4 (Hap2-4) of OsGA20ox5 provides valuable insights for drought-resistant breeding.

Oryza

A novel domain of unknown function 707 protein coordinates root growth and drought tolerance.

A well-developed root system is one of the morphological mechanisms through which xerophytes adapt to drought. However, the molecular mechanisms underlying root growth are not completely known. In this work, two domain of unknown function 707 (DUF707) proteins were identified as hub genes for the response of roots to drought stress in Lespedeza potaninii, a xerophytic subshrub. We found that angiosperm DUF707 proteins can be divided into two subfamilies. LpDUF707-1 expression was strongly induced under drought stress and abscisic acid (ABA) treatment in the roots of L. potaninii, and its promoter activity in the roots was significantly induced by drought stress and mannitol treatments. The overexpression of LpDUF707-1 significantly improved root growth and drought tolerance, whereas the silencing of LpDUF707-1 inhibited root growth and reduced drought tolerance. We further revealed that the LpOBP3.1 transcription factor directly binds to the promoter region of LpDUF707-1, thereby repressing its activity. LpOBP3.1 expression was strongly suppressed under drought stress and ABA treatment in the roots of L. potaninii. The overexpression of LpOBP3.1 significantly inhibited root growth and decreased drought tolerance, whereas LpOBP3.1-RNAi lines presented the opposite pattern. Collectively, our results demonstrated that this novel module regulates root growth and drought tolerance in L. potaninii, thus providing gene targets for the development of elite crop varieties with well-developed root-mediated drought tolerance.

Drought Resistance

MhSHINE2-like interacts with MhGRF3 to promote drought tolerance via modulating stomatal aperture in apple.

Drought poses a significant global challenge to agriculture, substantially reducing crop yields. Abscisic acid (ABA) plays a crucial role in response to drought stress. Nevertheless, the molecular mechanism underlying the ABA-mediated drought stress response in apple remains poorly understood. We identified a drought- and ABA-induced AP2/ERF transcription factor (TF), MhSHINE2-like, which positively regulates drought stress tolerance in apple. Biochemical analysis showed that MhSHINE2-like directly binds to the GAGA-rich element in the promoter of the ABA biosynthesis gene MhNCED3, promoting its transcription under drought stress. Overexpression of MhNCED3 promotes ABA accumulation and enhances apple drought tolerance by regulating stomatal closure under drought stress. Further studies revealed that MhSHINE2-like physically interacts with 14-3-3 protein, MhGRF3, which also contributes positively to drought tolerance. Notably, MhSHINE2-like and MhGRF3 function cooperatively to modulate the expression of downstream genes, promoting ABA accumulation, and consequently enhancing drought tolerance in apple. These findings reveal a regulatory network mediated by the combined effects of TFs and chaperone proteins, offering valuable genetic resources for the development of drought-tolerant apple cultivars.

Malus

WRKY14-DPB Module Enhances Drought Tolerance by Activating the Expression of UGT84B1 Involved in Hydrolyzable Tannin Biosynthesis.

Drought stress severely limits the growth and development of trees. Tannins, which serve as vital secondary metabolites in plant roots, help mitigate drought stress. The Lauraceae family, which holds major economic and ecological value, faces substantial developmental challenges due to its sensitivity to drought conditions. Despite this, research on the regulatory mechanisms governing tannin-specific accumulation under drought stress remains limited. In this study, we aim to explore how WRKY14 interacts with DPB to regulate the metabolism of hydrolyzable tannin (HT) via the key enzyme UGT84B1, thereby enhancing drought tolerance in Litsea cubeba, a main species within the Lauraceae family. The WRKY-DPB-UGT84B1 module was specifically expressed in roots in response to drought stress. LcUGT84B1 was found to generate 1-O-Galloyl-β-d-glucose in vitro and in overexpressing L. cubeba. Moreover, molecular biology and transformation experiments demonstrated that LcWRKY14 and LcDPB formed a complex that directly bound to the LcUGT84B1 promoter, activating its expression and thereby facilitating HT synthesis. Co-overexpression of LcWRKY14 and LcDPB significantly enhanced drought tolerance by increasing HT accumulation. These findings provide new insights into the regulatory mechanisms of the WRKY-DPB-UGT84B1 module in promoting drought tolerance and offer a potential breeding strategy for developing drought-resistant varieties.

Drought Resistance

The small nucleolar RNA NON-CODING RNA 1 negatively regulates drought tolerance in Arabidopsis thaliana.

Small nucleolar RNAs (snoRNAs) function in ribosome biogenesis, and many ribosome biogenesis-related genes were downregulated by osmotic stress, implying a negative role of snoRNAs in drought tolerance. A snoRNA, namely, the NON-CODING RNA 1 (NCR1) was studied for its roles in drought tolerance in Arabidopsis. In comparison with wild-type (WT) plants, the loss-of-function ncr1 mutant plants showed enhanced drought tolerance, which was restored in the NCR1-complemented plants, whereas the NCR1-overexpressing plants revealed a drought-sensitive phenotype. Physiological analyses revealed that the ncr1 plants had a higher leaf surface temperature, lower water loss rates, and improved cell membrane integrity compared with WT. Comparative leaf transcriptomics and proteomics suggested that wax biosynthesis, anthocyanin metabolism, and leaf senescence processes are regulated by NCR1 under both normal and water-deficit conditions. Under drought, an increase in wax and anthocyanin accumulations and a delay in leaf senescence in ncr1 plants, when compared with WT, supported the transcriptome and proteomics data. Additionally, the ncr1 plants exhibited higher abscisic acid (ABA) sensitivity and longer root hairs than WT. Collectively, our results suggest that NCR1 negatively regulates drought tolerance through modification of wax biosynthesis, anthocyanin accumulation, leaf senescence, cell membrane integrity, ABA responses, and root hair development.

Arabidopsis

Dissecting the genetic basis underlying drought tolerance at different development stages in soybean.

INTRODUCTION: Soybean is an indispensable crop supplying protein and oil for humans and animals, and playing an essential role in global food security. Drought represses soybean seed germination, reducing biomass accumulation and even inhibiting yield. METHODS: In order to dissect the genetic components underlying soybean drought tolerance during different development stage, a natural population containing 140 accessions was employed to evaluate seven drought tolerance-related traits under water-welled and drought stress conditions. Subsequently, genome-wide association study (GWAS) was conducted based on 150K single nucleotide polymorphism (SNP) markers of "Zhongdouxin-1". And the drought tolerance coefficient of seven different traits were analyzed with seven GWAS models. RESULTS: A total of 1807 significant SNPs were detected across 20 chromosome, including 569 SNPs for germination stage, and 1242 SNPs for seedling stage. Of 569 SNPs identified in germination stage, 354 SNPs on chromosomes 2, 7, 13, 14, and 17 accounting for 62.21%. Among 1242 SNPs found in seedling stage, 869 SNPs on chromosomes 11, 14, 15, 17 and 18 accounting for 69.97%. Moreover, among 1807 significant SNPs, 163 SNPs exhibited pleiotropic effects, of which 23 were located in exon, 21 in intron, 12 in 5'UTR or 3'UTR and 11 in upstream or downstream. Furthermore, 249 stable SNPs were detected by more than four GWAS models. According to these stable SNPs, RNA expression levels and gene annotations, four causal genes (Glyma.02G080200, Glyma.11G056200, Glyma.12G188900, and Glyma.18G110200) conferring soybean drought tolerance were detected, which participated in ethylene stimulus response, water deprivation response, and proteolysis. DISCUSSION: Collectively, 249 stable SNPs, 163 pleiotropic SNPs and four candidate genes identified in present study provided promising molecular resources and reliable foundation for drought resistance improvement and marker-assisted selective breeding in soybean.

GWAS

Small nucleolar RNA HIDDEN TREASURE 2 reduces drought tolerance via multiple pathways in Arabidopsis.

Small nucleolar RNAs (snoRNAs) contribute to ribosome biogenesis and modulate various aspects of plant growth and development. Given that osmotic stress downregulates numerous genes associated with ribosome biogenesis in roots, we hypothesize that snoRNAs might function in modulating plant responses to osmotic and drought stresses. To prove this hypothesis, we assessed the role of a C/D-box snoRNA, namely the HIDDEN TREASURE 2 (HID2), in Arabidopsis thaliana responses to drought using both loss-of-function and overexpression approaches. Under drought conditions, the Arabidopsis hid2 mutant displayed a significantly higher survival rate than both wild-type (WT) and HID2-complemented plants, while HID2-overexpressing plants showed a lower survival rate than WT. A series of physiological assays indicated that the hid2 mutant maintained a slower rate of water loss and more intact cell membranes than WT plants under drought, which supported their drought-tolerant phenotype. Comparative leaf transcriptome and proteome analyses revealed that processes related to wax biosynthesis, senescence, and anthocyanin accumulation were differentially regulated between hid2 and WT plants under water-deficit conditions. Consistently, the hid2 mutant accumulated higher amounts of wax and anthocyanins and exhibited delayed leaf senescence relative to WT plants under drought. Additionally, the hid2 mutant showed improved ability to increase sensitivity to abscisic acid (ABA), scavenge reactive oxygen species (ROS), and extended root hairs. Overall, these findings demonstrate HID2's role as a negative modulator in Arabidopsis drought tolerance by negatively affecting cell membrane stability, wax and anthocyanin biosynthesis, senescence, ROS-scavenging capacity, ABA responsiveness, and root hair formation.

Arabidopsis

Genome-wide analysis of FATA associated with drought tolerance in tetraploid potato (Solanum tuberosum).

The cuticle represents the outer most protective barrier against biotic and abiotic stresses. It is composed of cutin and waxes and protects plants from desiccation, UV, cold, mechanical stresses, and pathogens. GWAS/BSAseq combined with SeqSNP analyses in an association panel of 34 potato cultivars had revealed that the acyl-ACP thioesterase FATA (Soltu.DM.06G033680.1) is significantly associated with drought tolerance in potato. Apart from three FATB genes, only one FATA gene is present in potato that has the highest homology to FATA2 in Arabidopsis. FATA is responsible for the export of C18:1 fatty acid from chloroplast into cytosol, which is necessary for the biosynthesis of cutin. A knockout mutant of AtFATA2 was analyzed with regard to the cuticle permeability and to drought tolerance as well as recovery. Loss of FATA function leads to higher sensibility to water deficit in Arabidopsis, but to no change in recovery. The increased permeability of the cuticle in the fata2 knockout mutant as shown indirectly by higher chlorophyll leaching might play a role in this. Haplotypes for FATA were identified for the two potato cultivars Albatros and Désirée. All Désirée haplotypes and Albatros haplotypes 1, 3 and 4 were also revealed by former potato pan genome studies, while Albatros haplotype 2 is unique and has not been described before. Protein models were developed to investigate the influence of different SNPs in the haplotypes on the predicted protein structure and especially the substrate cavity. In potato, protein modeling suggests that only the hypothetical isoform B of FATA might be able to process oleoyl-ACP, but not hypothetical isoform A. However, this hypothesis needs to be verified by enzyme activity assays.

FATA

Replacement of chromosome 3D with Thinopyrum chromosome 3St led to increased drought tolerance during the flowering stage in wheat.

The stable 3St(3D) substitution line offers promising genetic potential for improving drought tolerance in wheat during critical reproductive stages. The flowering stage is highly susceptible to drought, which significantly reduces wheat grain yield globally. Low genetic diversity in wheat further limits the discovery of optimal gene variants for breeding climate-resilient varieties. The substitution of chromosome 3D by a group 3 chromosome pair from Thinopyrum intermedium × Th. ponticum artificial hybrid was identified using in situ hybridization and genotyping-by-sequencing. This homoeologous substitution showed good functional compensation for grain yield and fertility, similar to the wheat parents ('Mv9kr1' and 'Mv Karizma') in field and greenhouse trials. The substitution line exhibits a semidwarf phenotype due to the Rht8 and Rht2 dwarfing alleles. Automated shoot phenotyping after a 10-day water withdrawal at flowering revealed efficient water preservation allowing to maintain photosynthetic functions, sustained photosynthetic activity, and less chlorophyll degradation, indicated by Normalized Difference Vegetation Index (NDVI) and modified Normalized Difference Index (mND705) values and moderate level of protective functions shown by the expression of stress-related genes. Compared to the wheat parents, the substitution line developed thicker roots with increased volume under drought, resulting in a lower surface-to-volume ratio. This may enhance water storage efficiency and help reduce yield loss under drought conditions.

Triticum

β-carotene enhances drought tolerance in fenugreek by modulating antioxidant defense and redox homeostasis.

Drought stress is one of the main abiotic factors that modulates the morphology and physiology of crops. This study investigated the effect of foliar application of β-carotene on the growth, physiological, and biochemical responses of fenugreek (Trigonella foenum-graecum L.) under drought stress conditions. A pot experiment was conducted using two varieties, Kasuri and Local, under two drought stress levels (control and 50% field capacity), and three β-carotene concentrations (0, 100, and 200 ppm) were applied. Drought stress significantly declined shoot fresh weight up to 35.02% and 58.04%, and shoot length to 17.12% and 17.14%, while increasing the root fresh weight by 133% and 26.2% and the root length to 109.1% and 13.4%, respectively, in the Kasuri methi and Local. Drought stress decreases the total Chl. by 55.4% and 59.3% and carotenoids 42.1% and 59.3% and increased the MDA by 6.35% and 24.2%, respectively, and the content of hydrogen peroxides increased by 12.05% and 44.2% in Kasuri and Local as compared to control. By the application of 200  ppm β-carotene, the shoot fresh weight increased by 95.06% and 66.7%, the shoot length increased by 49.6% and 44.5%, and the total Chl. increased by 194.3% and 144.3%, and carotenoids 71.6% and 63%, and MDA decreased by 14.7% and 15.8%, hydrogen peroxides 26.6% and 27.8%, in Kasuri methi and Local under drought stress conditions. Additionally, with the application of β-carotene, antioxidant enzyme activities (SOD, POD, and CAT) and osmoprotectants (total soluble proteins and sugars) improved significantly, indicating enhanced oxidative defense. Overall, foliar β-carotene application, especially at 200 ppm, proved highly effective in improving fenugreek's drought tolerance by enhancing antioxidant capacity, maintaining pigment stability, and supporting metabolic homeostasis, thereby highlighting its potential role in sustainable crop management under water-limited conditions.

beta Carotene