Abiotic Stress Tolerance In Wheat Research Articles

Assessment of salt tolerance in Algerian oasis wheat landraces: An examination of biochemical, physiological, and agronomical traits

Wheat landraces cultivated in the oases of Algeria are are know for their resistance to abiotic stresses as a result of the extreme environmental constraints of the Sahara. As such, these landraces represent valuable breeding material for improving abiotic stress tolerance in wheat. This study was conducted to evaluate salt tolerance of bread and durum wheat from the Algerian oases. Ten wheat landraces from the Algerian oases were grown under prolonged salinity stress (150 mM NaCl) in greenhouse conditions. Data were assessed for 19 physiological, biochemical, and agronomical traits. The wheat landraces exhibited considerable variation in their salinity stress tolerance. The membership function value of salt tolerance identified Oum RokbaElhamra, Khellouf and Zeghlou as the most tolerant landraces while Bourione was identified as sensitive. The salt-tolerant and moderately tolerant wheat landraces maintained stable yields under conditions of salinity stress. Regression models constructed from MFVS and salt tolerance coefficients showed that for bread wheat, amino acid content and grain yield accounted for most of the variation in MFVS, while for durum wheat, the number of grains per plant and Na+ content explained the majority of observed differences in MFVS. Correlation analysis showed that the MFVS was significantly associated with grain yield, selectivity between K+ and Na+, and plant height. The results confirm that Algerian oasis wheat landraces are a valuable source given their salt tolerance and could be utilized in breeding programs seeking to improve salinity stress resilience in wheat.

Unlocking the Genetic Basis of Abiotic Stress Tolerance in Wheat: Insights from Dif- ferential Expression Analysis and Machine Learning

Abiotic stresses such as heat and cold temperatures, salinity, and drought are threatening global food security by affecting crop quality and reproductivity. Wheat is the most essential staple crop in the world, its complex genome is the main barrier to finding valuable genes responsive to different stresses. Thus, in our study we conducted differential RNA-seq analysis to identify Differentially Expressed Genes (DEGs) involved in 4 different stresses such as drought, heat, freeze resistance, and water-deficit stress, then applied two machine learning models; the "Extra-tree regressor" and LIME algorithms to accurately predict and select the highly significant genes. Our findings identified a set of 36 significant genes, many of which play important roles in various molecular functions, cellular components, and biological processes related to the response or resistance to abiotic stress in wheat. For example, Hsp101b is a member of the heat shock protein family, which protects cells against stress by stabilizing proteins. BADH, an enzyme involved in the synthesis of stress hormones, is important for the plant’s response to different stresses. AGL14 is a member of the AGL protein family, which regulates gene expression and is involved in the plant’s response to drought, cold, and salinity stresses. This study demonstrates the prospects of the integration of bioinformatics tools as well as machine learning models to assess the genes responsible for wheat stress resistance, genes’ regulatory networks, and their functions in order to save time and cost to improve wheat productivity.

Role of silicon in abiotic stress tolerance in wheat

Role of silicon in abiotic stress tolerance in wheat

Mdivi-1 Induced Mitochondrial Fusion as a Potential Mechanism to Enhance Stress Tolerance in Wheat.

Simple SummaryMitochondria play a key role in providing energy to cells. This paper is dedicated to elucidating mitochondria-dependent mechanisms that may enhance abiotic stress tolerance in wheat. Mitochondria are constantly undergoing dynamic processes of fusion and fission. In plants, stressful conditions tend to favor mitochondrial fusion processes. The role of mitochondrial fusion was studied by applying Mdivi-1, an inhibitor of mitochondrial fission, to wheat roots subjected to a wounding stress. Increased mitochondrial functional activity and upregulation of genes involved in energy metabolism suggest that mitochondrial fusion is associated with a general activation of energy metabolism. Controlling mitochondrial fusion rates could change the physiology of wheat plants by altering the energy status of the cell and helping to reduce the effects of stress.Mitochondria play a key role in providing energy to cells. These organelles are constantly undergoing dynamic processes of fusion and fission that change in stressful conditions. The role of mitochondrial fusion in wheat root cells was studied using Mdivi-1, an inhibitor of the mitochondrial fragmentation protein Drp1. The effect of the inhibitor was studied on mitochondrial dynamics in the roots of wheat seedlings subjected to a wounding stress, simulated by excision. Treatment of the stressed roots with the inhibitor increased the size of the mitochondria, enhanced their functional activity, and elevated their membrane potentials. Mitochondrial fusion was accompanied by a decrease in ROS formation and associated cell damage. Exposure to Mdivi-1 also upregulated genes encoding the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and an energy sensor AMP-dependent protein sucrose non-fermenting-related kinase (SnRK1), suggesting that mitochondrial fusion is associated with a general activation of energy metabolism. Controlling mitochondrial fusion rates could change the physiology of wheat plants by altering the energy status of the cell and helping to mitigate the effects of stress.

Abiotic stress tolerance in wheat with emphasis on drought

Environmental change presents a significant hazard to most tropical and subtropical crops across the world. Drought stress is among the negative repercussions of environmental modification that affects agricultural development and output. It has a significant influence on the vegetative and propagative phases of plants. Considering the current and prospective nutrition demands of a growing populace, it is critical to target crop production in drought-prone rainfed areas. Crops respond to drought stress in various manners, including structural, physio-chemical, and molecular responses. Drought tolerance encompasses processes that operate at several geographical and temporal dimensions, ranging from immediate stomatal closure to crop production management. There are multiple genes in wheat that are responsible for drought resistance and generate various enzymes and proteins under drought conditions. This review focusses the current advances in wheat physio-chemical, and molecular adaptation to drought tolerance. The experimental data revealed that drought stress negatively impacts multiple physiological processes that occur in wheat plants during their various growth phases, including germination, vegetative growth, reproductive development, and maturity. Therefore, studying the drought-induced damage in wheat plants, as well as strategies for boosting drought tolerance, is critical for increasing wheat output. Furthermore, molecular genetics and breeding strategies for developing drought tolerance in wheat to boost yield and quality are discussed

Consensus genomic regions associated with multiple abiotic stress tolerance in wheat and implications for wheat breeding

In wheat, a meta-analysis was performed using previously identified QTLs associated with drought stress (DS), heat stress (HS), salinity stress (SS), water-logging stress (WS), pre-harvest sprouting (PHS), and aluminium stress (AS) which predicted a total of 134 meta-QTLs (MQTLs) that involved at least 28 consistent and stable MQTLs conferring tolerance to five or all six abiotic stresses under study. Seventy-six MQTLs out of the 132 physically anchored MQTLs were also verified with genome-wide association studies. Around 43% of MQTLs had genetic and physical confidence intervals of less than 1 cM and 5 Mb, respectively. Consequently, 539 genes were identified in some selected MQTLs providing tolerance to 5 or all 6 abiotic stresses. Comparative analysis of genes underlying MQTLs with four RNA-seq based transcriptomic datasets unravelled a total of 189 differentially expressed genes which also included at least 11 most promising candidate genes common among different datasets. The promoter analysis showed that the promoters of these genes include many stress responsiveness cis-regulatory elements, such as ARE, MBS, TC-rich repeats, As-1 element, STRE, LTR, WRE3, and WUN-motif among others. Further, some MQTLs also overlapped with as many as 34 known abiotic stress tolerance genes. In addition, numerous ortho-MQTLs among the wheat, maize, and rice genomes were discovered. These findings could help with fine mapping and gene cloning, as well as marker-assisted breeding for multiple abiotic stress tolerances in wheat.

The role of silicon in regulating physiological and biochemical mechanisms of contrasting bread wheat cultivars under terminal drought and heat stress environments.

The individual and cumulative effects of drought stress (DS) and heat stress (HS) are the primary cause of grain yield (GY) reduction in a rainfed agricultural system. Crop failures due to DS and HS are predicted to increase in the coming years due to increasingly severe weather events. Plant available silicon (Si, H4SiO4) has been widely reported for its beneficial effects on plant development, productivity, and attenuating physiological and biochemical impairments caused by various abiotic stresses. The current study investigated the impact of pre-sowing Si treatment on six contrasting wheat cultivars (four drought and heat stress-tolerant and two drought and heat stress-susceptible) under individual and combined effects of drought and heat stress at an early grain-filling stage. DS, HS, and drought-heat combined stress (DHS) significantly (p < 0.05) altered morpho-physiological and biochemical attributes in susceptible and tolerant wheat cultivars. However, results showed that Si treatment significantly improved various stress-affected morpho-physiological and biochemical traits, including GY (>40%) and yield components. Si treatment significantly (p < 0.001) increased the reactive oxygen species (ROS) scavenging antioxidant activities at the cellular level, which is linked with higher abiotic stress tolerance in wheat. With Si treatment, osmolytes concentration increased significantly by >50% in tolerant and susceptible wheat cultivars. Similarly, computational water stress indices (canopy temperature, crop water stress index, and canopy temperature depression) also improved with Si treatment under DS, HS, and DHS in susceptible and tolerant wheat cultivars. The study concludes that Si treatment has the potential to mitigate the detrimental effects of individual and combined stress of DS, HS, and DHS at an early grain-filling stage in susceptible and tolerant wheat cultivars in a controlled environment. These findings also provide a foundation for future research to investigate Si-induced tolerance mechanisms in susceptible and tolerant wheat cultivars at the molecular level.

A novel thaumatin-like protein from durum wheat, TdPR-5, is homologous to known plant allergens, responsive to stress exposure, and confers multiple-abiotic stress tolerances to transgenic yeast

Thaumatin-like proteins (TLPs) are highly complex group of Pathogenesis-Related proteins (PRs) recognized as human allergens. They are known to rapidly accumulate in high levels following stresses. Several members of TLPs were isolated from different plant species, but few were described in durum wheat. In this study, a PR-5 member, TdPR-5, was isolated from a Tunisian variety of durum wheat. Phylogenetic analysis showed that TdPR-5 protein shared high homology with TLPs isolated from several plant species. Allergenic assessment of TdPR-5, using Allermatch tool, revealed that TdPR-5 had significant identity with TLPs, known as plant allergens. qRT-PCR analysis revealed that TdPR-5 is robustly induced by drought, salt and heavy metals such as cadmium (Cd), copper (Cu) and zinc (Zn). Notably, TdPR-5 induction is concomitant with the induction of the durum wheat transcription factor TdSHN1 shown previously to control the expression of tobacco PR-5 gene when overexpressed in transgenic tobacco plants. Maximum fold-change in relative expression of TdPR-5 and TdSHN1 genes following stress treatments reached 6.5 times (mannitol 1 h) and 10 times (Cu 24 h), respectively. Heterologous expression of TdPR-5 in transgenic yeast conferred resistance to multiple abiotic stresses. These results indicated that TdPR-5 may play an important role in multiple abiotic stress tolerance in wheat. This study also provides valuable information regarding food safety. In fact, overexpression of strong transcription factors such as TdSHN1 or exposure of plants to stressful conditions can lead to an increase in the quantity of allergens in crops thereby increasing the risk for consumers with known allergy or sensitization.

Phosphoinositide-specific phospholipase C gene involved in heat and drought tolerance in wheat (Triticum aestivum L.).

Phosphoinositide-specific phospholipase C proteins mediate environmental stress responses in many plants. However, the potential of PI-PLC genes involved with abiotic stress tolerance in wheat remains un-explored. To study TaPLC1 genetic relation with wheat drought and heat resistance. The seedlings were treated with PI-PLC inhibitor U73122 at the single leaf stage. The seedlings were treated with drought and heat stress at the two leaf stage, and some physiological indexes and the expression profile of TaPLC1 gene were determined. And the TaPLC1 overexpression vector was transferred to Arabidopsis and selected to T3 generation for drought and heat stress treatment. After 4h of drought and heat stress, the SOD activity, MDA and soluble sugar content of the two cultivars with inhibitor were higher than those without inhibitor, the chlorophyll content decreased. CS seedlings showed significant wilting phenomenon, and TAM107 showed slight wilting. After the elimination of drought and heat stress, all seedling wilting gradually recovered, while the leaf tips of the two varieties treated with inhibitors began to wilt and turn yellow, which was more significant 5 days after the drought and heat stress, while the degree of spring wilting and yellow in CS was earlier than that in TAM107. The expression patterns of TaPLC1 gene were different in the two cultivars, but the expression levels reached the maximum at 30min of heat stress. The change of TaPLC1 expression in TAM107 without inhibitor treatment was significantly greater than that in CS. The expression level of TaPLC1 in the two cultivars under stress was significantly different between the two cultivars treated with inhibitor and untreated, and was lower than that of the normal plants under normal conditions. These results indicated that inhibition of TaPLC1 gene expression could enhance the sensitivity of seedlings to stress. In Arabidopsis, the root lengths of transgenic and wild-type seedlings were shortened after drought stress treatment, but the root lengths of transgenic plants decreased slightly. And the expression of TaPLC1 gene was significantly increased after drought and heat stress. This indicated that overexpression of TaPLC1 improved drought resistance of Arabidopsis. The results of this study suggest that TaPLC1 may be involved in the regulation mechanism of drought and heat stress in wheat.

Molecular and Cytogenetic Studies on Abiotic Stress tolerance in wheat

Molecular and Cytogenetic Studies on Abiotic Stress tolerance in wheat

Global profiling of alternative splicing landscape responsive to salt stress in wheat (Triticum aestivum L.)

Alternative splicing (AS) plays crucial roles during plant development especially in stress responses. Although many studies have been performed on AS, the function of which participating in abiotic stress responses is still not well known. To assess the interplay between AS and salt stress, genome-wide analyses of AS were performed. Totally, 11,141 genes were found exhibiting significant AS changes after salt stress treatment, and more AS events were identified in Chinese Spring (CS, salt-sensitive) (21,203) than in Qing Mai 6 (QM, salt-tolerant) (19,742). Meanwhile, wheat homeologous genes displayed differential AS responses under salt stress treatment, and 7235, 8143 and 7407 AS events were identified on subgenome A, B and D respectively. Comparison of AS events at different time after salt stress showed that 4747 and 4129 salt stress responsive AS events were characterized in CS and QM, respectively, and most AS events were induced at 48 h after salt stress (HAS) compared with the other three stages. Functional enrichment analysis found that abiotic stress responsive pathways tended to be enriched in partitioned differentially spliced genes (DSGs) between CS and QM after salt stress treatment, and Pfam classification showed that many stress related proteins were also enriched under salt stress condition. Thus, these results demonstrated that AS regulation may play key roles in response to salt stress, which, together with transcriptional regulation, contributes to abiotic stress tolerance in wheat.

Drought and heat stress tolerance screening in wheat using computed tomography

BackgroundImproving abiotic stress tolerance in wheat requires large scale screening of yield components such as seed weight, seed number and single seed weight, all of which is very laborious, and a detailed analysis of seed morphology is time-consuming and visually often impossible. Computed tomography offers the opportunity for much faster and more accurate assessment of yield components.ResultsAn X-ray computed tomographic analysis was carried out on 203 very diverse wheat accessions which have been exposed to either drought or combined drought and heat stress. Results demonstrated that our computed tomography pipeline was capable of evaluating grain set with an accuracy of 95–99%. Most accessions exposed to combined drought and heat stress developed smaller, shrivelled seeds with an increased seed surface. As expected, seed weight and seed number per ear as well as single seed size were significantly reduced under combined drought and heat compared to drought alone. Seed weight along the ear was significantly reduced at the top and bottom of the wheat spike.ConclusionsWe were able to establish a pipeline with a higher throughput with scanning times of 7 min per ear and accuracy than previous pipelines predicting a set of agronomical important seed traits and to visualize even more complex traits such as seed deformations. The pipeline presented here could be scaled up to use for high throughput, high resolution phenotyping of tens of thousands of heads, greatly accelerating breeding efforts to improve abiotic stress tolerance.

Bacillus velezensis 5113 Induced Metabolic and Molecular Reprogramming during Abiotic Stress Tolerance in Wheat

Abiotic stresses are main limiting factors for agricultural production around the world. Plant growth promoting rhizobacteria (PGPR) have been shown to improve abiotic stress tolerance in several plants. However, the molecular and physiological changes connected with PGPR priming of stress management are poorly understood. The present investigation aimed to explore major metabolic and molecular changes connected with the ability of Bacillus velezensis 5113 to mediate abiotic stress tolerance in wheat. Seedlings treated with Bacillus were exposed to heat, cold/freezing or drought stress. Bacillus improved wheat survival in all stress conditions. SPAD readings showed higher chlorophyll content in 5113-treated stressed seedlings. Metabolite profiling using NMR and ESI-MS provided evidences for metabolic reprograming in 5113-treated seedlings and showed that several common stress metabolites were significantly accumulated in stressed wheat. Two-dimensional gel electrophoresis of wheat leaves resolved more than 300 proteins of which several were differentially expressed between different treatments and that cold stress had a stronger impact on the protein pattern compared to heat and drought. Peptides maps or sequences were used for database searches which identified several homologs. The present study suggests that 5113 treatment provides systemic effects that involve metabolic and regulatory functions supporting both growth and stress management.

High intrinsic seed Zn concentration improves abiotic stress tolerance in wheat

Abiotic stresses are threatening wheat productivity across the globe, which is often associated with nutrient deficiencies. Zinc (Zn) is involved in many physiological processes of plants, and high intrinsic seed Zn concentrations may help to improve the resistance of wheat to abiotic stresses. Three separate experiments evaluated the effect of intrinsic seed zinc on bread wheat resistance to abiotic stresses, viz. waterlogging, drought and salinity. One-week-old wheat seedlings raised from seeds containing either 49 mg (high), 42 mg (medium), or 35 mg (low) Zn kg−1 grain were exposed to waterlogging or drought stress for one week or until harvest. Salinity stress was applied at sowing for one week or until harvest. Plants with high intrinsic seed Zn performed better than those with medium or low Zn concentrations under each stress, including lower malondialdehyde contents and total antioxidant activities and more proline. The grain yield in plants from high, medium and low seed Zn concentrations increased by 10.5–48%, 12.2–21.5% and 7.7–21% under waterlogging, drought and salinity stress, respectively. Plants with high intrinsic seed Zn concentrations produced higher wheat grain yields than those with lower levels under abiotic stress by reducing oxidative damage and improving the growth and uptake of nutrients.

Omics Approaches for Engineering Wheat Production under Abiotic Stresses.

Abiotic stresses greatly influenced wheat productivity executed by environmental factors such as drought, salt, water submergence and heavy metals. The effective management at the molecular level is mandatory for a thorough understanding of plant response to abiotic stress. Understanding the molecular mechanism of stress tolerance is complex and requires information at the omic level. In the areas of genomics, transcriptomics and proteomics enormous progress has been made in the omics field. The rising field of ionomics is also being utilized for examining abiotic stress resilience in wheat. Omic approaches produce a huge amount of data and sufficient developments in computational tools have been accomplished for efficient analysis. However, the integration of omic-scale information to address complex genetics and physiological questions is still a challenge. Though, the incorporation of omic-scale data to address complex genetic qualities and physiological inquiries is as yet a challenge. In this review, we have reported advances in omic tools in the perspective of conventional and present day approaches being utilized to dismember abiotic stress tolerance in wheat. Attention was given to methodologies, for example, quantitative trait loci (QTL), genome-wide association studies (GWAS) and genomic selection (GS). Comparative genomics and candidate genes methodologies are additionally talked about considering the identification of potential genomic loci, genes and biochemical pathways engaged with stress resilience in wheat. This review additionally gives an extensive list of accessible online omic assets for wheat and its effective use. We have additionally addressed the significance of genomics in the integrated approach and perceived high-throughput multi-dimensional phenotyping as a significant restricting component for the enhancement of abiotic stress resistance in wheat.

Identifying potential molecular factors involved in Bacillus amyloliquefaciens 5113 mediated abiotic stress tolerance in wheat.

Abiotic stressors are main limiting factors for agricultural production around the world. Plant growth-promoting bacteria have been successfully used to improve abiotic stress tolerance in several crops including wheat. However, the molecular changes involved in the improvement of stress management are poorly understood. The present investigation addressed some molecular factors involved in bacterially induced plant abiotic stress responses by identifying differentially expressed genes in wheat (Triticum aestivum) seedlings treated with the beneficial bacterium Bacillus amyloliquefaciens subsp. plantarum UCMB5113 prior to challenge with abiotic stress conditions such as heat, cold or drought. cDNA-AFLP analysis revealed differential expression of more than 200 transcript-derived fragments (TDFs) in wheat leaves. Expression of selected TDFs was confirmed using RT-PCR. DNA sequencing of 31 differentially expressed TDFs revealed significant homology with both known and unknown genes in database searches. Virus-induced gene silencing of two abscisic acid-related TDFs showed different effects upon heat and drought stress. We conclude that treatment with B.amyloliquefaciens 5113 caused molecular modifications in wheat in order to induce tolerance against heat, cold and drought stress. Bacillus treatment provides systemic effects that involve metabolic and regulatory functions supporting both growth and stress management.

Plant growth-promoting rhizobacteria enhance wheat salt and drought stress tolerance by altering endogenous phytohormone levels and TaCTR1/TaDREB2 expression.

Abiotic stresses such as salt and drought represent adverse environmental conditions that significantly damage plant growth and agricultural productivity. In this study, the mechanism of the plant growth-promoting rhizo-bacteria (PGPR)-stimulated tolerance against abiotic stresses has been explored. Results suggest that PGPR strains, Arthrobacter protophormiae (SA3) and Dietzia natronolimnaea (STR1), can facilitate salt stress tolerance in wheat crop, while Bacillus subtilis (LDR2) can provide tolerance against drought stress in wheat. These PGPR strains enhance photosynthetic efficiency under salt and drought stress conditions. Moreover, all three PGPR strains increase indole-3-acetic acid (IAA) content of wheat under salt and drought stress conditions. The SA3 and LDR2 inoculations counteracted the increase of abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylate (ACC) under both salt and drought stress conditions, whereas STR1 had no significant impact on the ABA and ACC content. The impact of PGPR inoculations on these physiological parameters were further confirmed by gene expression analysis as we observed enhanced levels of the TaCTR1 gene in SA3-, STR1- and LDR2-treated wheat seedlings as compared to uninoculated drought and salt stressed plants. PGPR inoculations enhanced expression of TaDREB2 gene encoding for a transcription factor, which has been shown to be important for improving the tolerance of plants to abiotic stress conditions. Our study suggest that PGPR confer abiotic stress tolerance in wheat by enhancing IAA content, reducing ABA/ACC content, modulating expression of a regulatory component (CTR1) of ethylene signaling pathway and DREB2 transcription factor.

Evaluating interspecific wheat hybrids based on heat and drought stress tolerance

Three durum and three bread wheat genotypes were crossed to produce three tetraploid, three hexaploid and nine interspecific (pentaploid) F1 hybrids. All genotypes were evaluated for heat tolerance in the field and for drought using polyethylene glycol in vitro. Chromosome numbers and meiotic behavior in pentaploid F1 hybrids (2n=5x=35, genomes AABBD) were confirmed. Heat stress significantly reduced grain yield/plant and 1000-kernel weight (1000-KW), while grain protein content (GPC) was increased. Drought caused a significant reduction in root length, shoot length and seedling fresh weight, whereas root/shoot ratio was increased. P3 (durum), P4 (bread) and their pentaploid F1 hybrid could be considered as the most heat-tolerant genotypes. However, P2 (durum), P6 (bread) and their F1 were most tolerant to drought. The addition of a D genome single dose into pentaploid F1 hybrids obviously reduced grain yield/plant, 1000-KW and seedling traits, however GPC was increased. Moderate to high broad-sense heritability and genetic advance were obtained for the most investigated traits. Grain yield/plant was strongly positively correlated with stress tolerance index (STI), yield index (YI), mean productivity (MP), geometric mean productivity (GMP) and harmonic mean (HM) under heat stress and with root length under drought condition, suggesting that STI, YI, MP, GMP and HM are powerful indices for heat tolerance, while root length is most effective for drought. Successful interspecific hybridization obtained in the study is only an initial step for desired genes introgression. Successive progenies are going to be evaluated for further genetic studies aiming at improving abiotic stress tolerance in wheat.

Meta‐Analysis of Wheat QTL Regions Associated with Adaptation to Drought and Heat Stress

ABSTRACTDrought and heat are the two most important environmental constraints to wheat (Triticum aestivum L.) production globally and are predicted to become more severe with global climate change. A number of recent studies have reported quantitative trait loci (QTL) for yield and agronomic traits in drought and heat‐stressed environments and for physiological traits that contribute to improved performance under stress. The objective of this study was to perform a meta‐analysis of reported QTL to identify meta‐QTL (MQTL) associated with adaptation to drought and heat stress. In the studies analyzed, QTL were reported for 81 different traits across a range of environments including both field and controlled experiments. A total of 854 individual QTL were reported, with 502 associated with drought stress, 234 with heat stress, and 118 with physiological traits in nonstressed environments. Individual QTL clustered into 66 MQTL regions distributed throughout the genome. There were 43 MQTL that co‐localized for both drought and heat stress, 20 specific for drought stress, 2 specific for heat stress, and 1 MQTL specific for physiological traits in nonstressed environments. Quantitative trait loci for plant height, days to maturity, kernel weight, spike density, and canopy temperature were most significantly associated with QTL for yield. Integration of 137 single nucleotide polymorphism (SNP) markers for heat‐ and drought‐responsive candidate genes identified 50 SNPs within MQTL confidence intervals, including genes involved in sugar metabolism, scavenging of reactive oxygen species, and abscisic‐acid‐induced stomatal closure. Identified MQTL and candidate genes can be targeted for future studies and genetic improvement of abiotic stress tolerance in wheat.

Isolation and molecular characterization of a novel WIN1/SHN1 ethylene-responsive transcription factor TdSHN1 from durum wheat (Triticum turgidum. L. subsp. durum).

Over the last decade, APETALA2/Ethylene Responsive Factor (AP2/ERF) proteins have become the subject of intensive research activity due to their involvement in a variety of biological processes. This research led to the identification of AP2/ERF genes in many species; however, little is known about these genes in durum wheat, one of the most important cereal crops in the world. In this study, a new member of the AP2/ERF transcription factor family, designated TdSHN1, was isolated from durum wheat using thermal asymetric interlaced PCR (TAIL-PCR) method. Protein sequence analysis showed that TdSHN1 contained an AP2/ERF domain of 63 amino acids and a putative nuclear localization signal (NLS). Phylogenetic analysis showed that TdSHN1 belongs to a group Va protein in the ERF subfamily which contains the Arabidopsis ERF proteins (SHN1, SHN2, and SHN3). Expression of TdSHN1 was strongly induced by salt, drought, abscisic acid (ABA), and cold. In planta, TdSHN1 protein was able to activate the transcription of GUS reporter gene driven by the GCC box and DRE element sequences. In addition, TdSHN1 was targeted to the nucleus when transiently expressed in tobacco epidermal cells. In transgenic yeast, overexpression of TdSHN1 increased tolerance to multiple abiotic stresses. Taken together, the results showed that TdSHN1 encodes an abiotic stress-inducible, transcription factor which confers abiotic stress tolerance in yeast. TdSHN1 is therefore a promising candidate for improvement of biotic and abiotic stress tolerance in wheat as well as other crops.