Tolerant Wheat Research Articles

Superior glucose metabolism supports NH4+ assimilation in wheat to improve ammonium tolerance.

The use of slow-release fertilizers and seed-fertilizers cause localized high-ammonium (NH4 +) environments in agricultural fields, adversely affecting wheat growth and development and delaying its yield. Thus, it is important to investigate the physiological responses of wheat and its tolerance to NH4 + stress to improve the adaptation of wheat to high NH4 + environments. In this study, the physiological mechanisms of ammonium tolerance in wheat (Triticum aestivum) were investigated in depth by comparative analysis of two cultivars: NH4 +-tolerant Xumai25 and NH4 +-sensitive Yangmai20. Cultivation under hydroponic conditions with high NH4 + (5 mM NH4 +, AN) and nitrate (5 mM NO3 -, NN), as control, provided insights into the nuanced responses of both cultivars. Compared to Yangmai20, Xumai25 displayed a comparatively lesser sensitivity to NH4 + stress, as evident by a less pronounced reduction in dry plant biomass and a milder adverse impact on root morphology. Despite similarities in NH4 + efflux and the expression levels of TaAMT1.1 and TaAMT1.2 between the two cultivars, Xumai25 exhibited higher NH4 + influx, while maintaining a lower free NH4 + concentration in the roots. Furthermore, Xumai25 showed a more pronounced increase in the levels of free amino acids, including asparagine, glutamine, and aspartate, suggesting a superior NH4 + assimilation capacity under NH4 + stress compared to Yangmai20. Additionally, the enhanced transcriptional regulation of vacuolar glucose transporter and glucose metabolism under NH4 + stress in Xumai25 contributed to an enhanced carbon skeleton supply, particularly of 2-oxoglutarate and pyruvate. Taken together, our results demonstrate that the NH4 + tolerance of Xumai25 is intricately linked to enhanced glucose metabolism and optimized glucose transport, which contributes to the robust NH4 + assimilation capacity.

Genotypic Differences in Morphological, Physiological and Agronomic Traits in Wheat (Triticum aestivum L.) in Response to Drought.

Drought is one of the main environmental factors affecting crop growth, and breeding drought-tolerant cultivars is one of the most economic and effective ways of increasing yields and ensuring sustainable agricultural production under drought stress. To facilitate the breeding of drought-tolerant wheat, this study was conducted to evaluate genotypic differences in the drought tolerance of 334 wheat genotypes collected from China and Australia with the aim of screening for drought-tolerant and -sensitive genotypes and to elucidate the corresponding physiological mechanisms. A hydroponic-air experiment (roots exposed to air for 7 h/d and continued for 6 d) showed significant genotypic differences in shoot and root dry weights among the genotypes. The relative shoot and root dry weights, expressed as the percentage of the control, showed a normal distribution, with variation ranges of 20.2-79.7% and 32.8-135.2%, respectively. The coefficients of variation were in the range of 18.2-22.7%, and the diversity index was between 5.71 and 5.73, indicating a rich genetic diversity among the wheat genotypes for drought tolerance. Using phenotypic differences in relative dry weights in responses to drought stress, 20 of each of the most drought-tolerant and drought-sensitive genotypes were selected; these were further evaluated in pot experiments (watering withheld until the soil moisture content reached four percent). The results showed that the trends in drought tolerance were consistent with the hydroponic-air experiment, with genotypes W147 and W235 being the most drought-tolerant and W201 and W282 the most sensitive. Significant genotypic differences in water use efficiency in response to drought were observed in the pot experiment, with the drought-tolerant genotypes being markedly higher and the two sensitive genotypes being no different from the control. A marked increase in bound water content in the drought stress plants was observed in the two drought-tolerant genotypes, while a decrease occurred in the free water. The reductions in photochemical efficiencies of PSII, transpiration rates, net photosynthesis rates, chlorophyll contents and stomatal conduction in the drought-sensitive genotypes W201 and W282 under drought stress were higher than the two tolerant genotypes. This study provides a theoretical guide and germplasm for the further genetic improvement of drought tolerance in wheat.

Drought stress effect, tolerance, and management in wheat – a review

Drought stress effect, tolerance, and management in wheat – a review

Vermicompost application upregulates morpho-physiological and antioxidant defense to conferring drought tolerance in wheat

Drought stress is an ever‐present threat to wheat growth, development, and productivity, especially in arid and semi-arid areas where rainfall is an essential aid to agriculture. The application of vermicompost has been proven to be an efficient approach to combat the drought-induced growth and developmental limitation of wheat plants and to promote cost-effective and sustainable crop production. A wire-house pot experiment was conducted to examine the effects of cow manure vermicompost on morpho-physiological and biochemical attributes of wheat seedlings under different deficit water levels. The treatments were included: three drought levels; control (70 % of field capacity (FC, D0)), mild drought (45 % of FC, D1), and severe drought (30 % of FC, D1), four vermicompost application rates; control, 4, 6 and 8 t ha−1 (designated as VT0, VT1, VT2 and VT3, respectively), and two contrasting wheat cultivars; Faisalabad-08 (drought tolerant) and Galaxy-13 (drought sensitive). Results showed that vermicompost application improved crop performance under control and drought stress conditions where VT2 depicted significantly higher values in both cultivars, particularly under drought stress. Under severe drought, VT2 increased root fresh weight by 6.13 and 10.63 %, shoot fresh weight by 15.62 % and 23.58 %, root dry weight by 40.81 % and 50 % and shoot dry weight by 20.68 and 22.22 % in Faisalabad-08 and Galaxy-13, respectively. Also, VT2-treated seedlings exhibited significantly higher gas exchange attributes, chlorophyll pigments and antioxidative enzyme activities under drought conditions. Among cultivars, Faisalabad-08 was found comparatively more drought tolerant than Galaxy-13. Our findings demonstrated that drought severely affects morphological, physiological, and biochemical attributes of wheat. However, soil applied vermicompost proved beneficial for improved morphophysiological and biochemical traits under the regime of drought stress in wheat.

Upregulation of Wheat Heat Shock Transcription Factor TaHsfC3-4 by ABA Contributes to Drought Tolerance.

Drought stress can seriously affect the yield and quality of wheat (Triticum aestivum). So far, although few wheat heat shock transcription factors (Hsfs) have been found to be involved in the stress response, the biological functions of them, especially the members of the HsfC (heat shock transcription factor C) subclass, remain largely unknown. Here, we identified a class C encoding gene, TaHsfC3-4, based on our previous omics data and analyzed its biological function in transgenic plants. TaHsfC3-4 encodes a protein containing 274 amino acids and shows the basic characteristics of the HsfC class. Gene expression profiles revealed that TaHsfC3-4 was constitutively expressed in many tissues of wheat and was induced during seed maturation. TaHsfC3-4 could be upregulated by PEG and abscisic acid (ABA), suggesting that this Hsf may be involved in the regulation pathway depending on ABA in drought resistance. Further results represented that TaHsfC3-4 was localized in the nucleus but had no transcriptional activation activity. Notably, overexpression of TaHsfC3-4 in Arabidopsis thaliana pyr1pyl1pyl2pyl4 (pyr1pyl124) quadruple mutant plants complemented the ABA-hyposensitive phenotypes of the quadruple mutant including cotyledon greening, root elongation, seedling growth, and increased tolerance to drought, indicating positive roles of TaHsfC3-4 in the ABA signaling pathway and drought tolerance. Furthermore, we identified TaHsfA2-11 as a TaHsfC3-4-interacting protein by yeast two-hybrid (Y2H) screening. The experimental data show that TaHsfC3-4 can indeed interact with TaHsfA2-11 in vitro and in vivo. Moreover, transgenic Arabidopsis TaHsfA2-11 overexpression lines exhibited enhanced drought tolerance, too. In summary, our study confirmed the role of TaHsfC3-4 in response to drought stress and provided a target locus for marker-assisted selection breeding to improve drought tolerance in wheat.

Transcriptome and biochemical analysis in hexaploid wheat with contrasting tolerance to iron deficiency pinpoints multi-layered molecular process

Iron (Fe) is an essential plant nutrient that is indispensable for many physiological activities. This study is an effort to identify the molecular and biochemical basis of wheat genotypes with contrasting tolerance towards Fe deficiency. Our physiological experiments performed at the early growth stage in cv. Kanchan (KAN) showed Fe deficiency tolerance, whereas cv. PBW343 (PBW) was susceptible. Under Fe deficient condition, KAN showed delayed chlorosis, high SPAD values, and low malondialdehyde content compared to PBW, indicative of Fe deficient condition. Comparative shoot transcriptomics revealed increased expression of photosynthetic pathway genes in PBW, further suggesting its sensitivity to Fe fluctuations. Under Fe deficiency, both the cultivars showed distinct molecular re-arrangements such as high expression of genes involved in Fe uptake (including membrane transporters) and its remobilization. Specifically, in KAN these changes lead to high root phytosiderophores (PS) biosynthesis and its release, resulting in enhanced Fe translocation index. Utilizing the non-transgenic TILLING (Targeting Induced Lesions in Genomes) technology, we identified TaZIFL4.2D as a putative PS efflux transporter. Characterization of the wheat TILLING lines indicated that TaZIFL4.2 functions in PS release and Fe acquisition, thereby imparting tolerance to Fe deficiency. Altogether, this work highlights the mechanistic insight into Fe deficiency tolerance of hexaploid wheat, thus enabling breeders to select suitable genotypes to utilize nutrients for maximum yields.

Identification and expression analysis of genomic regions associated with the traits contributing to lodging tolerance in wheat (Triticum aestivum L.)

Crop lodging, either stem breaking/stem bending or root lodging, is a major concern for farmers worldwide. In the present study, meta-QTLs, ortho-MQTLs and candidate genes related to lodging and its associated traits were identified using 836 of the 1269 known QTLs retrieved from 107 QTL mapping studies published during 1998–2022. The study resulted in the identification of 86 MQTLs with an average confidence interval (CI) of 1.66 cM (4.26-fold reduction) as against a CI of > 7.08 cM in the initial QTLs. Out of 86 MQTLs, a subset of 12 MQTLs demonstrated stability and robustness, earning them the title of breeders’ MQTLs. These selections were made based on criteria such as the number of initial QTLs involved, small CI, high LOD scores, and PVE values. Furthermore, leveraging synteny and collinearity facilitated the identification of 10 ortho-MQTLs shared between wheat and maize. Further, in silico expression analysis allowed the detection of 53 significantly expressed candidate genes encoding different proteins/products including the following: F-box protein, GDSL lipase/esterases, SANT/Myb domain transcription factor, pectin esterase inhibitor domain, glycoside hydrolase family, protein kinase domain, zinc finger domain, cytochrome P450, UDP-glucuronosyl/UDP-glucosyltransferase, glycosyltransferase 61 etc. In addition, 26 lodging tolerance genes from Arabidopsis, rice, and maize were also utilized to identify 34 wheat homologues in wheat MQTL regions. Among these, three genes TraesCS2D02G256600 (TaEREB114-2D), TraesCS7B02G340100 (TaIRX14-7B), and TraesCS1B02G347600 (TaGA2ox4-1B) were prioritized for qRT-PCR-based expression analysis in one lodging-tolerant (i.e., WH-1105) and one lodging-susceptible (i.e., WH-1184) variety. When comparing these two varieties, we found higher relative expression levels of these three genes in the second basal internode at the milky endosperm stage of the lodging-tolerant variety. The MQTLs, ortho-MQTLs, and candidate genes (CGs) identified in this study can be utilized for marker-assisted selection to improve lodging tolerance and enhance our understanding of the molecular basis of lodging tolerance in wheat.

Priming of seeds with cyanobacteria improved tolerance in wheat (Triticum aestivum L.) during post-germinative drought stress

Priming of seeds with cyanobacteria improved tolerance in wheat (Triticum aestivum L.) during post-germinative drought stress

QTL mapping: insights into genomic regions governing component traits of yield under combined heat and drought stress in wheat.

Drought and heat frequently co-occur during crop growth leading to devastating yield loss. The knowledge of the genetic loci governing component traits of yield under combined drought and heat stress is essential for enhancing the climate resilience. The present study employed a mapping population of 180 recombinant inbred lines (RILs) derived from a cross between GW322 and KAUZ to identify quantitative trait loci (QTLs) governing the component traits of yield under heat and combined stress conditions. Phenotypic evaluation was conducted across two consecutive crop seasons (2021-2022 and 2022-2023) under late sown irrigation (LSIR) and late sown restricted irrigation (LSRI) conditions at the Indian Council of Agricultural Research Institute-Indian Agricultural Research Institute (ICAR-IARI), New Delhi. Various physiological and agronomic traits of importance were measured. Genotyping was carried out with 35K SNP Axiom breeder's genotyping array. The linkage map spanned a length of 6769.45cM, ranging from 2.28cM/marker in 1A to 14.21cM/marker in 5D. A total of 35 QTLs were identified across 14 chromosomes with 6B containing the highest (seven) number of QTLs. Out of 35 QTLs, 16 were major QTLs explaining the phenotypic variance greater than 10%. The study identified eight stable QTLs along with two hotspots on chromosomes 6B and 5B. Five QTLs associated with traits thousand-grain weight (TGW), normalized difference vegetation index (NDVI), and plant height (PH) were successfully validated. Candidate genes encoding antioxidant enzymes, transcription factors, and growth-related proteins were identified in the QTL regions. In silico expression analysis highlighted higher expression of transcripts TraesCS2D02G021000.1, TraesCS2D02G031000, TraesCS6A02G247900, and TraesCS6B02G421700 under stress conditions. These findings contribute to a deeper understanding of the genetic architecture underlying combined heat and drought tolerance in wheat, providing valuable insights for wheat improvement strategies under changing climatic conditions.

Genome-wide analysis of the Tritipyrum NAC gene family and the response of TtNAC477 in salt tolerance

NAC transcription factors are widely distributed in the plant kingdom and play an important role in the response to various abiotic stresses in plant species. Tritipyrum, an octoploid derived from hybridization of Triticum aestivum (AABBDD) and Thinopyrum elongatum (EE), is an important genetic resource for integrating the desirable traits of Th. elongatum into wheat. In this study, we investigated the tissue distribution and expression of Tritipyrum NAC genes in the whole genomes of T. aestivum and Th. elongatum after obtaining their complete genome sequences. Based on phylogenetic relationships, conserved motifs, gene synthesis, evolutionary analysis, and expression patterns, we identified and characterized 732 Tritipyrum NAC genes. These genes were divided into six main groups (A, B, C, D, E, and G) based on phylogenetic relationships and evolutionary studies, with members of these groups sharing the same motif composition. The 732 TtNAC genes are widely distributed across 28 chromosomes and include 110 duplicated genes. Gene synthesis analysis indicated that the NAC gene family may have a common ancestor. Transcriptome data and quantitative polymerase chain reaction (qPCR) expression profiles showed 68 TtNAC genes to be highly expressed in response to various salt stress and recovery treatments. Tel3E01T644900 (TtNAC477) was particularly sensitive to salt stress and belongs to the same clade as the salt tolerance genes ANAC019 and ANAC055 in Arabidopsis. Pearson correlation analysis identified 751 genes that correlated positively with expression of TtNAC477, and these genes are enriched in metabolic activities, cellular processes, stimulus responses, and biological regulation. TtNAC477 was found to be highly expressed in roots, stems, and leaves in response to salt stress, as confirmed by real-time PCR. These findings suggest that TtNAC477 is associated with salt tolerance in plants and might serve as a valuable exogenous gene for enhancing salt tolerance in wheat.

Genome-wide association study of agronomic traits related to nitrogen use efficiency in Henan wheat

BackgroundNitrogen use efficiency (NUE) is closely related to crop yield and nitrogen fertilizer application rate. Although NUE is susceptible to environments, quantitative trait nucleotides (QTNs) for NUE in wheat germplasm populations have been rarely reported in genome-wide associated study.ResultsIn this study, 244 wheat accessions were phenotyped by three NUE-related traits in three environments and genotyped by 203,224 SNPs. All the phenotypes for each trait were used to associate with all the genotypes of these SNP markers for identifying QTNs and QTN-by-environment interactions via 3VmrMLM. Among 279 QTNs and one QTN-by-environment interaction for low nitrogen tolerance, 33 were stably identified, especially, one large QTN (r2 > 10%), qPHR3A.2, was newly identified for plant height ratio in one environment and multi-environment joint analysis. Among 52 genes around qPHR3A.2, four genes (TraesCS3A01G101900, TraesCS3A01G102200, TraesCS3A01G104100, and TraesCS3A01G105400) were found to be differentially expressed in low-nitrogen-tolerant wheat genotypes, while TaCLH2 (TraesCS3A01G101900) was putatively involved in porphyrin metabolism in KEGG enrichment analyses.ConclusionsThis study identified valuable candidate gene for low-N-tolerant wheat breeding and provides new insights into the genetic basis of low N tolerance in wheat.

Screening and identification of heat tolerance in Indian wheat genotypes using generalized regression neural network (GRNN) model

The present study using a generalized regression neural network (GRNN) model was carried out to check the effect of high temperature on five Indian bread wheat genotypes, namely, C306, K7903, CBW12, HD2329, and HD2428, and to develop an algorithm for the screening and identification of heat tolerance in wheat. A highly significant differential survivability in response to the temperature induction response technique with germinating seeds was observed for the five wheat genotypes. Maximum survivability was observed for C306 and K7903, whereas HD2329 and HD2428 showed minimum survival in response to lethal temperature stress. Similarly, at the mature plant stage, in response to heat treatment of 34°C/26°C (day/night), all five wheat genotypes showed a significant difference in chlorophyll a fluorescence, total chlorophyll content, and the reduction of 1,1- diphenyl-2-picryl-hydrazyl (DPPH) in response to heat treatment. The genotypes, C306, K7903, and CBW12 showed better performance for all the chlorophyll a fluorescence parameters under study including Fo, Fv/Fm, qL, qP, NPQ, θPSII, ETR, along with the total chlorophyll content and DPPH reduction, in contrast, the genotypes, HD2329 and HD2428 performed poorly for all parameters including chlorophyll a fluorescence parameters, total chlorophyll, and DPPH reduction. Higher inflection temperature and peak temperature were observed in C306 and K7903, in contrast, HD2329 and HD2428 showed significantly lower inflection temperature and peak temperature. Higher expression of the selected genes involved in photosynthesis and ROS scavenging was observed in C306 and K7903 relative to HD2329 and HD2428. On the basis of the different chlorophyll a fluorescence parameters, the algorithm was developed for the calculation of the heat susceptibility index. The algorithm was independently checked for the identification and segregation of all the five wheat genotypes taken in this study as tolerant, moderate, and susceptible. For all the genotypes, the algorithm was able to predict the heat susceptibility of the genotypes with high accuracy. Hence, the algorithm in combination with chlorophyll a fluorescence can be used for the screening of wheat and other plant species in response to abiotic stress, especially heat stress.

Genetic Basis for Salt Stress Tolerance in Wheat through Using ISSR Markers

Genetic Basis for Salt Stress Tolerance in Wheat through Using ISSR Markers

Enhancing water stress tolerance of bread wheat during seed germination and seedling emergence: caffeine-induced modulation of antioxidative defense mechanisms.

Better crop stand establishment, a function of rapid and uniform seedling emergence, depends on the activities of germination-related enzymes, which is problematic when there is insufficient soil moisture. Different ways are in practice for counteracting this problem, including seed priming with different chemicals, which are considered helpful in obtaining better crop stand establishment to some extent through improved seed germination and seedling emergence. In this growth room experiment, caffeine was used as a seed priming agent to improve germination under moisture scarcity. Polyethylene glycol-8000 (18%) was added to Hoagland's nutrient solution to create drought stress (-0.65 MPa). The experiment was arranged in a completely randomized design (CRD), having four replications of each treatment. A newly developed wheat genotype SB-1 was used for the experimentation. Different doses of caffeine, i.e., 4 ppm, 8 ppm, 12 ppm, and 16 ppm, including no soaking and water soaking, were used as seed priming treatments. Water deficit caused oxidative stress and adversely affected the seed germination, seedling vigor, activities of germination enzymes, photosynthetic pigments, and antioxidative defense mechanism in roots and shoots of seedlings. Caffeine seed priming ameliorated the negative effects of water deficit on seed germination and seedling vigor, which was attributed to the reduction in lipid peroxidation and improvement in the activities of germination-related enzymes like glucosidase, amylase, and protease. Conclusively, seed priming with 12 ppm caffeine outperformed the other treatments and hence is recommended for better crop stand establishment under conditions of soil moisture deficit.

Integrative indexes reveal the tolerance of winter wheat to different overwinter freezing injury.

Winter wheat (Triticum aestivum L.) is a crucial crop that guarantees food supply in the North China Plain (NCP). As the frequency of extreme cold events increases, it is necessary to explore the freezing resistance of different wheat varieties in order to clarify planting boundaries and help with risk assessment. In this study, 2-year controlled experiments were conducted to explore the effect of freezing temperatures (T air) and freezing durations on three winterness types. A set of indexes were used to characterize the subfreezing stress on wheat tiller, leaf, and final yield. Logistical regressions were used to quantify the temperature threshold for 10%, 30%, and 50% of freezing injury. The results showed that the lower temperature threshold of tiller (LT) varied from -9.6 to -15.9°C, -10.7 to -19.1°C and -11.4 to -21.2°C for LT10, LT30, and LT50, respectively. The difference between LT and yield loss (YL) indexes reduced with decreased winterness types and was -0.1 to 3.4°C, -0.7 to 2.1°C, and 0.3 to 0.9°C higher compared with YL thresholds for winterness, semi-winterness, and weak-winterness types, respectively. The average minimum soil temperature was 7.5, 4.8, and 4.2°C higher than T air for 1-, 2-, and 3-day treatment, respectively. Soil effective negative accumulated temperature hours (TSEh) ranged from 6.9 to 12.0, 48.4 to 6.9, and 84.7 to 106.9°C·h for 10%, 30%, and 50% tiller mortality, respectively. Freezing treatment with T air < -12, -9, and -8°C obviously decreased leaf Fv/Fm for the three varieties and Fv/Fm declined obviously after 5 days of recovery under field conditions. Our results provided multiple indexes for quantifying subfreezing damage in practical wheat production and could shed light on future risk assessment.

Precise phenotyping approach or characterization of terminal heat tolerance in bread wheat (Triticum aestivum L.)

Precise phenotyping approach or characterization of terminal heat tolerance in bread wheat (Triticum aestivum L.)

Multi-trait selection for agronomic performance and drought tolerance among durum wheat genotypes evaluated under rainfed and irrigated environments

Summary Durum wheat (Triticum turgidum L. subsp. durum) is a major crop in the Mediterranean region, widely grown for its nutritional value and economic importance. Durum wheat breeding can contribute to global food security through the introduction of new cultivars exhibiting drought tolerance and higher yield potential in the Mediterranean environments. In this study, 25 durum wheat genotypes (23 elite breeding lines and two national checks) were evaluated for five drought-adaptive traits (days to heading, days to maturity, plant height, 1000-kernel weight and grain yield) and eight drought tolerance indices including stress tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP), stress susceptibility index, tolerance index, yield index, yield stability index and drought response index under rainfed and irrigated conditions during three cropping seasons (2019–2022). Multi-trait stability index (MTSI) technique was applied to select genotypes with higher grain yield, 1000-kernel weight, plant stature and early flowering and maturity simultaneously; as well as for higher drought tolerance in each and across years. A heat map correlation analysis and principal component analysis were applied to study the relationships among drought tolerance indices and the pattern of variation among genotypes studied. Factor analysis was applied for identification of traits that contributed most in stability analyses. Significant and positive correlations were observed among the three drought tolerance indices of STI, GMP and MP with mean yields under both rainfed and irrigated conditions in each and across years, suggest the efficiency of these indices as selection criteria for improved drought tolerance and yield performance in durum wheat. The genotypes ranked based on MTSI varied from environment to environment, showing the impact of environment on genotypes performance, but several of the best performing lines were common across environments. According to MTSI for agronomic traits, the breeding lines G20, G6, G25 and G18 exhibited highest performance and trait stability across environmental conditions, and the selected genotypes had strength towards grain yield, 1000-kernel weight and earliness. Using the MTSI, breeding lines G20, G5, G16 and G7 were selected as drought tolerant genotypes with high mean performance. Breeding line G20 from ICARDA germplasm showed highest trait stability performance and drought tolerance across environments. The MTSI was a useful tool for selecting genotypes based on their agronomic performance and drought tolerance that could be exploited for identification and selection of elite genotypes with desired multi-traits. Based on the results, breeding lines G20 and G6 should be recommended for short-term release programme and/ or utilized in durum wheat population improvement programme for agronomic performance and drought tolerance traits that tolerate climate variations.

Genetic variability, correlation and path analysis of yield and yield contributing characters in wheat (Triticum aestivum L.) under normal and terminal heat stress condition

Genetic variability and characters association studies play a pivotal role in enhancing selection efficiency under stress condition in plants. Therefore, the study was aimed at assessing the impact of terminal heat stress on various morpho-physiological traits and their association in wheat under control and terminal heat stress condition. The experiment was conducted using thirty-five wheat genotypes in a Randomized Complete Block design (RCBD) plots on three different sowing dates to induce terminal heat stress. A range of 11 morpho-physiological parameters were assessed. All of the traits showed significant variations under studied conditions. Estimates of the genotypic and phenotypic coefficients of variation (GCV and PCV) showed that PCV was higher than GCV indicating large environmental influence on the expression of the traits under study. High GCV and PCV were observed in grain per plant and yield per plant in both normal and heat stress conditions. Chlorophyll content, grain per plant and yield per plant showed highest heritability with high genetic advance (GA) under both normal and terminal heat stress condition. According to the results of the path co-efficient analysis, grain per plant had a strong positive connection with grain yield and plant height and days to 50% flowering had a negative correlation with grain yield per plant under both normal and stress condition. Canopy temperature has direct negative effect on yield in stress condition. The identified traits can be used as effective selection criteria under terminal heat stress condition to develop high yielding heat tolerant wheat variety.

Enhancing Wheat Tolerance to Cadmium Stress through Moringa Leaf Extract Foliar Application.

Cadmium, a hazardous heavy metal prevalent in plants and soil, poses a significant threat to human health, particularly as approximately 60% of the global population consumes wheat, which can accumulate high levels of Cd through its roots. This uptake leads to the translocation of Cd to the shoots and grains, exacerbating the potential health risks. However, promising results have been observed with the use of moringa leaf extract (MLE) foliar spray in mitigating the adverse effects of Cd stress. The current experiment was conducted to find out the Cd stress tolerance of wheat varieties V1 = Akbar-19 and V2 = Dilkash-2020 under exogenous spray of MLE. The treatments of this study were T0 = 0% MLE + 0 µM Cd, T1 = 3% MLE + 0 µM Cd, T2 = 0% MLE + 400 µM Cd, and T3 = 3% MLE + 400 µM Cd. Cd stress demonstrated a significant reduction in morphological attributes as shoot and root fresh weight (22%), shoot and root dry weight (24.5%), shoot and root length (22.5%), area of leaf and number of leaves 30.5%, and photosynthetic attributes (69.8%) in comparison with control. Exposure of wheat plants to Cd toxicity cause oxidative stress, increased H2O2, and MDA up to 75% while foliar application of MLE reduced the activities of reactive oxygen species (ROS). The activity of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbic acid (AsA) increased up to 81.5% as well as organic osmolytes such as phenolics, total soluble proteins, and total soluble sugars were improved up to 77% by MLE applications under Cd stress. Higher accumulation of ionic contents root Na+ (22%) and Cd (44%) was documented in plants under Cd stress as compared to control, while uptake of root mineral ions Ca2+ and K+ was 35% more in MLE-treated plants. In crux, Cd toxicity significantly declined the growth, photosynthetic, and biochemical parameters while 3% MLE application was found effective in alleviating the Cd toxicity by improving growth and physiological parameters while declining reactive oxygen species and root Na+ as well as Cd uptake in wheat.

Designing of specific primers for different allelic forms of the DREB gene in bread wheat

The DREB transcription factor gene, which is considered the main component of the signaling network that regulates stress tolerance, was downloaded from the D genome of wheat whose genome was read from the EnsemblPlants database within the framework of the International Consortium on Wheat Genome Sequencing (Triticum aestivum IWGSC), and the intron-exon composition, domain structure and allelic forms were determined. The AP2 domain, which is responsible for the binding of the DREB protein to the target site on DNA, was found to be located in exon 2, and 14 single nucleotide polymorphisms (SNPs) causing amino acid changes in this area of the gene were determined. For the C/T allele, which leads to the replacement of valine at the 31st amino acid in the DREB protein with isoleucine, 5 pairs of primers meeting the requirements of RT-PCR were designed and tested experimentally, and 2 pairs of primers were found to be effective for the determination of this allele. Determination of SNPs that cause overexpression of the DREB gene is important for the future development of tolerant wheat varieties that can produce high yields under stress conditions by using the site-specific editing capabilities of CRISPR-Cas genome technology.