Drought Tolerance In Soybean Research Articles

GmTRAB1, a Basic Leucine Zipper Transcription Factor, Positively Regulates Drought Tolerance in Soybean (Glycine max. L)

The basic leucine zipper (bZIP) transcription factors play crucial roles in plant resistance to environmental challenges, but the biological functions of soybean bZIP members are still unclear. In this study, a drought-related soybean bZIP gene, GmTRAB1, was analyzed. The transcript of GmTRAB1 was upregulated under drought, ABA, and oxidative stresses. Overexpression of GmTRAB1 improved the osmotic stress tolerance of transgenic Arabidopsis and soybean hairy roots associated with increased proline content and activity of antioxidant enzymes and reduced accumulations of malonaldehyde and reactive oxide species. However, RNA interference silencing of GmTRAB1 in the soybean hairy roots improved drought sensitivity. Furthermore, GmTRAB1 increased the sensitivity of transgenic plants to ABA and participated in modulating ABA-regulated stomatal closure upon drought stress. In addition, GmTRAB1 stimulated the transcript accumulation of drought-, ABA-, and antioxidant-related genes to respond to drought. Collectively, this research will contribute to understanding the molecular mechanisms of bZIP transcription factors in soybean’s resistance to drought.

Soybean Drought Tolerance and Escape: Field Trial Assessment of Yield, Maturity Groups and Smooth-Wrinkled Seed Coats in Kazakhstan

Soybean Drought Tolerance and Escape: Field Trial Assessment of Yield, Maturity Groups and Smooth-Wrinkled Seed Coats in Kazakhstan

Mild water deficit at seed filling stage promotes drought-tolerant soybean production formation and flavonoids accumulation

Soybean is an important crop for both grain and oil use. Appropriate agricultural managements increase crop productivity quantity and chemical nutrition quality. This study utilized two soybean varieties HN44(drought-tolerant) and SN14 (drought-sensitive)to analyze mechanism effect of light drought stress on instantaneous water use efficiency(WUEi), yield and isoflavone content by changes in the transcriptome and metabolome during the early seed-filling stage. The results showed that light drought stress can improve WUEi, stimulate the yield potential and increase the content of Daidzin and 6''-O-malonyldaidzin of HN44. In addition, under light drought stress, the differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) in HN44 and SN14 were significantly enriched in the biosynthetic pathways of flavonoids and isoflavones. The flavonoid metabolites in HN44 increased, while those in SN14 decreased. Through the different expression patterns of DEGs and DAMs in the two varieties, differential genes and differential metabolites were screened out, such as CHS, HCT, F3H, HIDH, IF7GT, VR, p-coumaroylquinic, and 6''-O-Malonylglycitin. These genes and metabolites can provide theoretical basis for the selection breeding of drought-tolerant soybean varieties and the evaluation of drought-resistant resources. The findings provided important agronomic strategies for improving the yield, bioactive substances, and water resource management of crop soybeans.

Morphological Assessment of Drought Stress Tolerant Soybean Genotypes in Bangladesh

Soybean (Glycine max (L.) Merr) is the most important commercial grain legume and oil seed crop which represents the most important plant source of vegetable oil and protein in the world. The water stress tolerance of the fifty soybean genotypes was evaluated in a glasshouse at the Bangladesh Institute of Nuclear Agriculture (BINA). The study was carried out to identify the drought tolerant soybean genotype(s) for improving yield under rainfed conditions in Bangladesh. Drought stress was induced by withholding water completely from 21 days after emergence. The water stress was continued until wilting symptom persisted on plant overnight. Water stress caused an overall reduction in some morphological and yield contributing characters such as plant hight, number of branches plant-1, internode length, pod plant-1, seeds pod-1, hundred (100) seeds weight and finally the seed yield of soybean. The studied genotypes were categorized into four groups based on their yield reduction under drought stress conditions. Five genotypes YESOY-4, PK-416, Shohag, SBM-09 and Binasoybean-6 were categorized as tolerant (<35% yield reduction), fourteen genotypes were categorized as moderately tolerant (35%-60% yield reduction), twenty five genotypes were categorized as moderately susceptible (61%-80% yield reduction) and rest six genotypes were categorized as susceptible (>80% yield reduction). These five genotypes YESOY-4, PK-416, Shohag, SBM-09 and Binasoybean-6 study further for developing drought tolerant soybean verities which may be helpful for quality oil seed production.

NMR Fingerprinting of Conventional and Genetically Modified Soybean Plants with AtAREB1 Transcription Factors.

Drought stress impacts soybean yields and physiological processes. However, the insertion of the activated form of the AtAREB1 gene in the soybean cultivar BR16, which is sensitive to water deficit, improved the drought response of the genetically modified plants. Thus, in this study, we used 1H NMR in solution and solid-state NMR to investigate the response of genetically modified soybean overexpressing AtAREB1 under water deficiency conditions. We achieved that drought-tolerant soybean yields high content of amino acids isoleucine, leucine, threonine, valine, proline, glutamate, aspartate, asparagine, tyrosine, and phenylalanine after 12 days of drought stress conditions, as compared to drought-sensitive soybean under the same conditions. Specific target compounds, including sugars, organic acids, and phenolic compounds, were identified as involved in controlling sensitive soybean during the vegetative stage. Solid-state NMR was used to study the impact of drought stress on starch and cellulose contents in different soybean genotypes. The findings provide insights into the metabolic adjustments of soybean overexpressing AREB transcription factors in adapting to dry climates. This study presents NMR techniques for investigating the metabolome of transgenic soybean plants in response to the water deficit. The approach allowed for the identification of physiological and morphological changes in drought-resistant and drought-tolerant soybean tissues. The findings indicate that drought stress significantly alters micro- and macromolecular metabolism in soybean plants. Differential responses were observed among roots and leaves as well as drought-tolerant and drought-sensitive cultivars, highlighting the complex interplay between overexpressed transcription factors and drought stress in soybean plants.

Genetic Control of Tolerance to Drought Stress in Wild Soybean (Glycine soja) at the Vegetative and the Germination Stages.

Drought stress, which is becoming more prevalent due to climate change, is a significant abiotic factor that adversely impacts crop production and yield stability. Cultivated soybean (Glycine max), a versatile crop for humans and animals, exhibits sensitivity to drought, resulting in reduced growth and development under drought conditions. However, few genetic studies have assessed wild soybean's (Glycine soja) response to drought stress. In this work, we conducted a genome-wide association study (GWAS) and analysis of wild soybean accessions to identify loci responsible for drought tolerance at the vegetative (n = 187) and the germination stages (n = 135) using the available resequencing data. The GWAS analysis of the leaf wilting score (LWS) identified eight single-nucleotide polymorphisms (SNPs) on chromosomes 10, 11, and 19. Of these, wild soybeans with both SNPs on chromosomes 10 (adenine) and 11 (thymine) produced lower LWS, indicating that these SNPs have an important role in the genetic effect on LWS for drought tolerance at the vegetative stage. At the germination stage, nine SNPs associated with five phenotypic measurements were identified on chromosomes 6, 9, 10, 13, 16, and 17, and the genomic regions identified at the germination stage were different from those identified for the LWS, supporting our previous finding that there may not be a robust correlation between the genes influencing phenotypes at the germination and vegetative stages. This research will benefit marker-assisted breeding programs aimed at enhancing drought tolerance in soybeans.

Evaluation of Soybean Drought Tolerance Using Multimodal Data from an Unmanned Aerial Vehicle and Machine Learning

Evaluation of Soybean Drought Tolerance Using Multimodal Data from an Unmanned Aerial Vehicle and Machine Learning

Understanding the molecular mechanisms of drought tolerance in wild soybean (Glycine soja) through multi-omics-based alternative splicing predictions

The absence of adequate moisture resulting from drought poses a significant threat to both the viability and productivity of soybean cultivation. Genetic variation in common soybeans has been noticeably reduced through continuous breeding, and wild relatives with wider genetic diversity are one of the best tools in the search for new tolerance genes. In this study, we selected 139 genes co-expressed at transcript and protein levels in response to drought in Glycine soja through a multi-omics analysis. Drought stress induced co-expression of transcripts and proteins involved in dopamine synthesis within tyrosine metabolism. Polyphenol oxidase, involved in the dopamine synthesis process, was uniquely identified in both DEGs and DEPs, with its protein abundance increased. Co-expression of 9-lipoxygenase during linoleic acid metabolism was confirmed, along with consistent protein accumulation. The co-expression profiling of transcripts and proteins suggests that they may influence their regulatory feedback loops or unknown regulatory mechanisms. Additionally, we predicted the regulation of alternative splicing (AS) in response to drought. AS was predicted for 139 co-expressed genes, and four drought-tolerance-related gene candidate groups were selected. The expression levels of four genes, FT1, CCR1L, RPL18, and uncharacterized LOC114422617, varied depending on their transcript isoforms under drought stress. The occurrence of AS under drought stress may play a role in eliminating susceptibility genes or inducing tolerance genes to adapt to drought stress. Overall, this study reveals a novel mechanism of drought adaptation in wild soybean by predicting the regulation of metabolic pathways and AS events at the transcriptome and proteome levels and presents potential targets for soybean breeding.

Appropriate Drought Training Induces Optimal Drought Tolerance by Inducing Stepwise H2O2 Homeostasis in Soybean.

Soybean is considered one of the most drought-sensitive crops, and ROS homeostasis can regulate drought tolerance in these plants. Understanding the mechanism of H2O2 homeostasis and its regulatory effect on drought stress is important for improving drought tolerance in soybean. We used different concentrations of polyethylene glycol (PEG) solutions to simulate the progression from weak drought stress (0.2%, 0.5%, and 1% PEG) to strong drought stress (5% PEG). We investigated the responses of the soybean plant phenotype, ROS level, injury severity, antioxidant system, etc., to different weak drought stresses and subsequent strong drought stresses. The results show that drought-treated plants accumulated H2O2 for signaling and exhibited drought tolerance under the following stronger drought stress, among which the 0.5% PEG treatment had the greatest effect. Under the optimal treatment, there was qualitatively describable H2O2 homeostasis, characterized by a consistent increasing amplitude in H2O2 content compared with CK. The H2O2 signal formed under the optimum treatment induced the capacity of the antioxidant system to remove excess H2O2 to form a primary H2O2 homeostasis. The primary H2O2 homeostasis further induced senior H2O2 homeostasis under the following strong drought and maximized the improvement of drought tolerance. These findings might suggest that gradual drought training could result in stepwise H2O2 homeostasis to continuously improve drought tolerance.

Soybean steroids improve crop abiotic stress tolerance and increase yield.

Sterols have long been associated with diverse fields, such as cancer treatment, drug development, and plant growth; however, their underlying mechanisms and functions remain enigmatic. Here, we unveil a critical role played by a GmNF-YC9-mediated CCAAT-box transcription complex in modulating the steroid metabolism pathway within soybeans. Specifically, this complex directly activates squalene monooxygenase (GmSQE1), which is a rate-limiting enzyme in steroid synthesis. Our findings demonstrate that overexpression of either GmNF-YC9 or GmSQE1 significantly enhances soybean stress tolerance, while the inhibition of SQE weakens this tolerance. Field experiments conducted over two seasons further reveal increased yields per plant in both GmNF-YC9 and GmSQE1 overexpressing plants under drought stress conditions. This enhanced stress tolerance is attributed to the reduction of abiotic stress-induced cell oxidative damage. Transcriptome and metabolome analyses shed light on the upregulation of multiple sterol compounds, including fucosterol and soyasaponin II, in GmNF-YC9 and GmSQE1 overexpressing soybean plants under stress conditions. Intriguingly, the application of soybean steroids, including fucosterol and soyasaponin II, significantly improves drought tolerance in soybean, wheat, foxtail millet, and maize. These findings underscore the pivotal role of soybean steroids in countering oxidative stress in plants and offer a new research strategy for enhancing crop stress tolerance and quality from gene regulation to chemical intervention.

Cover crop inclusion and residue retention improves soybean production and physiology in drought conditions

Soybean (Glycine max (L.) Merr.) planting has increased in central and western North Dakota despite frequent drought occurrences that limit productivity. Soybean plants need high photosynthetic and transpiration rates to be productive, but they also need high water use efficiency when water is limited. Crop residues and cover crops in crop rotations may improve soybean drought tolerance in northern Great Plains. We aimed to examine how a management practice that included cover crops and residue retention impacts agronomic, ecosystem water and carbon dioxide flux, and canopy-scale physiological attributes of soybeans in the northern Great Plains under drought conditions. The experiment consisted of two soybean fields over two years with business-as-usual (no-cover crops and spring wheat residue removal) and aspirational management (cover crops and spring wheat residue retention) during a drought year. We compared yield; aboveground biomass; green chromatic coordinates, and CO2 and H2O fluxes from eddy covariance, Phenocam images, and ancillary micrometeorological measurements. These measurements were used to derive ecosystem-scale physical, and physiological attributes with the ‘big leaf’ framework to diagnose underlying processes. Soybean yields were 29 % higher under drought conditions in the field managed in a system that included cover crops and residue retention. This yield increase was associated with a 5 day increase in the green-chromatic-coordinate defined maturity phenophase, increasing agronomic and intrinsic water use efficiency by 27 % and 33 %, respectively, increasing water uptake, and increasing the rubisco-limited photosynthetic capacity (Vcmax25) by 42 %. The inclusion of cover crops and residue retention into a cropping system improved soybean productivity because of differences in water use, phenology timing, and photosynthetic capacity. These results suggest that farmers can improve soybean productivity and yield stability by incorporating cover crops and residue retention into their management suite because these practices to facilitate more aggressive water uptake.

Natural variation of GmFNSII-2 contributes to drought resistance by modulating enzyme activity in soybean

As an essential crop that provides vegetable oil and protein, soybean (Glycine max (L.) Merr.) is widely planted all over the world. However, the scarcity of water resources worldwide has seriously impacted on the quality and yield of soybean. To address this, exploring excellent genes for improving drought resistance in soybean is crucial. In this study, we identified natural variations of GmFNSII-2 (flavone synthase II) significantly affect the drought resistance of soybeans. Through sequence analysis of GmFNSII-2 in 632 cultivated and 44 wild soybeans nine haplotypes were identified. The full-length allele GmFNSII-2C, but not the truncated allele GmFNSII-2A possessing a nonsense nucleotide variation, increased enzyme activity. Further research found that GmDREB3, known to increase soybean drought resistance, bound to the promoter region of GmFNSII-2C. GmDREB3 positively regulated the expression of GmFNSII-2C, increased flavone synthase abundance and improved the drought resistance. Furthermore, a single-base mutation in the GmFNSII-2C promoter generated an additional drought response element (CCCCT), which had stronger interaction strength with GmDREB3 and increased its transcriptional activity under drought conditions. The frequency of drought-resistant soybean varieties with Hap 1 (Pro:GmFNSII-2C) has increased, suggesting that this haplotype may be selected during soybean breeding. In summary, GmFNSII-2C could be used for molecular breeding of drought-tolerant soybean.

Expression Patterns and Molecular Mechanisms Regulating Drought Tolerance of Soybean [Glycine max (L.) Merr.] Conferred by Transcription Factor Gene GmNAC19.

NAC transcription factors are commonly involved in the plant response to drought stress. A transcriptome analysis of root samples of the soybean variety 'Jiyu47' under drought stress revealed the evidently up-regulated expression of GmNAC19, consistent with the expression pattern revealed by quantitative real-time PCR analysis. The overexpression of GmNAC19 enhanced drought tolerance in Saccharomyces cerevisiae INVSc1. The seed germination percentage and root growth of transgenic Arabidopsis thaliana were improved in comparison with those of the wild type, while the transgenic soybean composite line showed improved chlorophyll content. The altered contents of physiological and biochemical indices (i.e., soluble protein, soluble sugar, proline, and malondialdehyde) related to drought stress and the activities of three antioxidant enzymes (i.e., superoxide dismutase, peroxidase, and catalase) revealed enhanced drought tolerance in both transgenic Arabidopsis and soybean. The expressions of three genes (i.e., P5CS, OAT, and P5CR) involved in proline synthesis were decreased in the transgenic soybean hairy roots, while the expression of ProDH involved in the breakdown of proline was increased. This study revealed the molecular mechanisms underlying drought tolerance enhanced by GmNAC19 via regulation of the contents of soluble protein and soluble sugar and the activities of antioxidant enzymes, providing a candidate gene for the molecular breeding of drought-tolerant crop plants.

Development of KASP markers assisted with soybean drought tolerance in the germination stage based on GWAS.

Soybean [Glycine max(L.)Merr.] is a leading oil-bearing crop and cultivated globally over a vast scale. The agricultural landscape in China faces a formidable challenge with drought significantly impacting soybean production. In this study, we treated a natural population of 264 Chinese soybean accessions using 15% PEG-6000 and used GR, GE, GI, RGR, RGE, RGI and ASFV as evaluation index. Using the ASFV, we screened 17 strong drought-tolerant soybean germplasm in the germination stage. Leveraging 2,597,425 high-density SNP markers, we conducted Genome-Wide Association Studies (GWAS) and identified 92 SNPs and 9 candidate genes significantly associated with drought tolerance. Furthermore, we developed two KASP markers for S14_5147797 and S18_53902767, which closely linked to drought tolerance. This research not only enriches the pool of soybean germplasm resources but also establishes a robust foundation for the molecular breeding of drought tolerance soybean varieties.

Identification of major QTLs for drought tolerance in soybean, together with a novel candidate gene, GmUAA6.

Drought tolerance is a complex trait in soybean that is controlled by polygenetic quantitative trait loci (QTLs). In this study, wilting score, days-to-wilting, leaf relative water content, and leaf relative conductivity were used to identify QTLs associated with drought tolerance in recombinant inbred lines derived from a cross between a drought-sensitive variety, Lin, and a drought-tolerant variety, Meng. A total of 33 drought-tolerance QTLs were detected. Of these 17 were major QTLs. In addition, 15 were novel drought-tolerance QTLs. The most predominant QTL was on chromosome 11. This was detected in at least three environments. The overlapped mapping interval of the four measured traits was 0.2 cM in genetic distance (about 220 kb in physical length). Glyma.11g143500 (designated as GmUAA6), which encodes a UDP-N-acetylglucosamine transporter, was identified as the most likely candidate gene. The allele of GmUAA6 from Lin (GmUAA6Lin) was associated with improved soybean drought tolerance. Overexpression of GmUAA6Lin in Arabidopsis and soybean hairy roots enhanced drought tolerance. Furthermore, a 3-bp insertion/deletion (InDel) in the coding sequence of GmUAA6 explained up to 49.9% of the phenotypic variation in drought tolerance-related traits, suggesting that this InDel might be used in future marker-assisted selection of drought-tolerant lines in soybean breeding programs.

In-Depth Analysis of Physiological, Biochemical, and Molecular Bases of Drought Tolerance in Soybeans

In-Depth Analysis of Physiological, Biochemical, and Molecular Bases of Drought Tolerance in Soybeans

GWAS and transcriptome analysis reveal key loci associated with drought tolerance in soybean

Genome-wide association and gene expression studies were conducted to identify key genes and markers associated with drought tolerance. GWAS panel consisting around 300 diverse soybean accessions were phenotyped for morpho-physiological traits under control and drought stress condition for three years during 2019-2021. Genotyping by Sequencing (GBS) of GWAS panel identified 66300 SNPs distributed over all the 20 chromosomes and were used for association analysis. GWAS analysis revealed closely located significant SNPs on chromosome 4 (50500762, 52098616 and 53008801) and chromosome 16 (32371663, 33082976 and 33283177). Key candidate genes related to MYB family, cell signaling gene (GPCR), salicylic acid synthesis, oxidative stress, auxin and ABA synthesis pathway were identified. Further few tolerant and susceptible haplotypes were also identified for real-time based expression analysis under drought stress condition.

Elevated CO2 concentration enhances drought resistance of soybean by regulating cell structure, cuticular wax synthesis, photosynthesis, and oxidative stress response

The atmospheric [CO2] and the frequency and intensity of extreme weather events such as drought are increased, leading to uncertainty to soybean production. Elevated [CO2] (eCO2) partially mitigates the adverse effects of drought stress on crop growth and photosynthetic performance, but the mitigative mechanism is not well understood. In this study, soybean seedlings under drought stress simulated by PEG-6000 were grown in climate chambers with different [CO2] (400 μmol mol−1 and 700 μmol mol−1). The changes in anatomical structure, wax content, photosynthesis, and antioxidant enzyme were investigated by the analysis of physiology and transcriptome sequencing (RNA-seq). The results showed that eCO2 increased the thickness of mesophyll cells and decreased the thickness of epidermal cells accompanied by reduced stomatal conductance, thus reducing water loss in soybean grown under drought stress. Meanwhile, eCO2 up-regulated genes related to wax anabolism, thus producing more epidermal wax. Under drought stress, eCO2 increased net photosynthetic rate (PN), ribulose-1,5-bisphosphate carboxylase/oxygenase activity, and alerted the gene expressions in photosynthesis. The increased sucrose synthesis and decreased sucrose decomposition contributed to the progressive increase in the soluble saccharide contents under drought stress with or without eCO2. In addition, eCO2 increased the expressions of genes associated with peroxidase (POD) and proline (Pro), thus enhancing POD activity and Pro content and improving the drought resistance in soybean. Taken together, these findings deepen our understanding of the effects of eCO2 on alleviating drought stress in soybean and provide potential target genes for the genetic improvement of drought tolerance in soybean.

Drought Tolerance in Soybean (Glycine max L. Merr.) Genotypes during the Flowering Stage of Development

Aims: To access the responses of 22 soybean genotypes under drought stress during the flowering stage of development.
 Study Design: A completely randomized experimental design (CRD) was adopted in this study. Five seeds of each of the 22 soybean genotypes were planted in 12-liter (L) plastic buckets (with holes at the bottom) containing sandy loam soil. There was one genotype per pot with three replications. The setup was repeated to represent experimental (drought-stressed (DS) and control (well-watered (WW) groups.
 Place and Duration of Study: Teaching and Research Farm of the School of Agriculture, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana in 2019.
 Methodology: Twenty-one exotic soybean genotypes and a local variety were assessed for their responses to drought stress at the flowering stage of development using pot experiment in the greenhouse. One group (experimental) was exposed to drought stress by withholding water for 15 days whilst the other group (control) was watered regularly at three-day intervals. Data collected were the number of leaves, plant height, stem girth, leaf area, and number of flowers, at 5, 10, and 15 days after treatment (DAT) and relative leaf water content at 15 DAT. The number of days to permanent wilting of the genotypes was also recorded.
 Results: Drought stress reduced the number of leaves and plant height significantly (P-values = 0.033, 0.000) and (P-values = 0.004, 0.000) at 10 and 15 days after drought treatment respectively. Also, stem girth, leaf area, and number of flowers were significantly reduced at all sampling dates (P-value = 0.002, 0.000, 0.000), (P-values = 0.004, 0.000, 0.000) and (P-values = 0.009, 0.000, 0.000) respectively. At 15 DAT, drought significantly (P < 0.001) reduced relative leaf water content. Genotypes TGX-1989-11F and TGX-1987-62F were the first and last to wilt at 7 days and 16 days after rewatering respectively.
 Conclusion: The pot screening method revealed that the number of leaves, plant height, stem girth, leaf area, number of flowers, relative leaf water content, and days to permanent wilting differed significantly (P = 0.05) at 15 days of drought exposure.

Jasmonic acid priming augments antioxidant defense and photosynthesis in soybean to alleviate combined heat and drought stress effects

In the aftermaths of global warming, plants are more frequently exposed to the combination of heat stress and drought in natural conditions. Jasmonic acid (JA) has been known to modulate numerous plant adaptive responses to diverse environmental stresses. However, the function of JA in regulating plant responses to the combined effects of heat and drought remains underexplored. In this study, we elucidated the functions of JA in enhancing the combined heat and drought tolerance of soybean (Glycine max). Our results showed that priming with JA improved plant biomass, photosynthetic efficiency and leaf relative water content, which all together contributed to the improved performance of soybean plants under single and combined heat and drought conditions. Exposure to single and combined heat and drought conditions caused oxidative damage in soybean leaves. Priming soybean plants, which were exposed to single and combined heat and drought conditions, with JA, on the other hand, substantially quenched the reactive oxygen species-induced oxidative burden possibly by bolstering their antioxidant defense system. Together, our findings provide direct evidence of the JA-mediated protective mechanisms in maintaining the optimal photosynthetic rate and plant performance under combined heat and drought conditions.