Bread Wheat Triticum Aestivum Research Articles

Genotype by environment interaction and stability study in bread wheat (Triticum aestivum L.) genotypes in Guji Zone, Southern Ethiopia

Genotype by environment interaction and stability study in bread wheat (Triticum aestivum L.) genotypes in Guji Zone, Southern Ethiopia

Morphological and Agronomical Characterization in Bread Wheat (Triticum aestivum L.) Germplasm and Combined Study of Heritability, Genetic Variance, Genetic Advances and Association of Characters

The present experiment was carried out during Rabi 2021-2022 at Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut-250110 (U.P.). The material used in the present study comprised 103 germplasm accessions of Wheat (Triticum aestivum L.) having variability for various agronomic and morphological characters were obtained from the available germplasm in the Department of Genetics & Plant Breeding, SVPUA&T, Meerut. The number of genotypes are 103 including four check (DBW-71, DBW-222, DBW-173, HD-3226), the Plot size is10 row 2.5m length spaced at 0.25m and the date of sowing is 20 December, 2021 on Augmented experimental design. Twelve observations were recorded. In each plot, five plants from each genotype were arbitrarily selected and tagged to record the observations studied characteristics except days to 50 % flowering and days to maturity they were recorded on plot basis. The highest value of biological yield per plant was estimated in CSW-18 (45.16g), DBW-621 (51.45%) recorded a high value of harvest index and the maximum grain yield is from CSW-18 (15.94) g. High heritability coupled with high genetic advance observed for gluten content, grain yield per plant, biological yield per plant, harvest index and number of productive tillers per plant.

Exploring natural genetic diversity in a bread wheat multi-founder population: Dual imaging of photosynthesis and stomatal kinetics.

A better understanding of crop phenotype under dynamic environmental conditions will help inform the development of new cultivars with superior adaptation to constantly changing field conditions. Recent research has shown that optimising photosynthetic and stomatal conductance traits holds promise for improved crop performance. However, standard phenotyping tools such as gas-exchange systems are limited by their throughput. In this work, a novel approach based on a bespoke gas-exchange chamber allowing combined measurement of the quantum yield of photosystem II (PSII) with an estimation of stomatal conductance via thermal imaging, was used to phenotype a range of bread wheat (Triticum aestivum L.) genotypes, that were a sub-set of a multi-founder experimental population. Datasets were further supplemented by measurement of photosynthetic capacity and stomatal density. First, we showed that measurement of stomatal traits using our dual imaging system compared to standard IRGA methods showed good agreement between the two methods (R2=0.86) for the rapidity of stomatal opening (Ki), with the dual-imager method resulting in less intra-genotype variation. Using the dual-imaging methods, and traditional approaches we found broad and significant variation in key traits, including photosynthetic CO2 uptake at saturating light and ambient CO2 concentration (Asat), photosynthetic CO2 uptake at saturating light and elevated CO2 concentration (Amax), the maximum velocity of Rubisco for carboxylation (Vcmax), time for stomatal opening (Ki), and leaf evaporative cooling. Anatomical analysis revealed significant variation in flag leaf adaxial stomatal density. Associations between traits highlighted significant relationships between leaf evaporative cooling, leaf stomatal conductance under low (gsmin) and high (gsmax) light intensity, and the operating efficiency of PSII (Fq'/Fm'), highlighting the importance of stomatal conductance and stomatal rapidity in maintaining optimal leaf temperature for photosynthesis in wheat. Additionally, gsmin and gsmax were positively associated, indicating that potential combination of preferable traits (i.e. inherently high gsmax, low Ki and maintained leaf evaporative cooling) are present in wheat. This work highlights for the first time the effectiveness of thermal imaging in screening dynamic stomatal conductance in a large panel of wheat genotypes. The wide phenotypic variation observed suggested the presence of exploitable genetic variability in bread wheat for dynamic stomatal conductance traits and photosynthetic capacity for targeted optimisation within future breeding programs.

Genomic prediction of synthetic hexaploid wheat upon tetraploid durum and diploid Aegilops parental pools.

Bread wheat (Triticum aestivum L.) is a globally important food crop, which was domesticated about 8-10,000 years ago. Bread wheat is an allopolyploid, and it evolved from two hybridization events of three species. To widen the genetic base in breeding, bread wheat has been re-synthesized by crossing durum wheat (Triticum turgidum ssp. durum) and goat grass (Aegilops tauschii Coss), leading to so-called synthetic hexaploid wheat (SHW). We applied the quantitative genetics tools of "hybrid prediction"-originally developed for the prediction of wheat hybrids generated from different heterotic groups - to a situation of allopolyploidization. Our use-case predicts the phenotypes of SHW for three quantitatively inherited global wheat diseases, namely tan spot (TS), septoria nodorum blotch (SNB), and spot blotch (SB). Our results revealed prediction abilities comparable to studies in 'traditional' elite or hybrid wheat. Prediction abilities were highest using a marker model and performing random cross-validation, predicting the performance of untested SHW (0.483 for SB to 0.730 for TS). When testing parents not necessarily used in SHW, combination prediction abilities were slightly lower (0.378 for SB to 0.718 for TS), yet still promising. Despite the limited phenotypic data, our results provide a general example for predictive models targeting an allopolyploidization event and a method that can guide the use of genetic resources available in gene banks.

Novel alleles of MFT‐A and MFT‐B1 appear to impact wheat preharvest sprouting in Triticum aestivum and Triticum turgidum ssp. durum

AbstractBackground and ObjectivesPreharvest sprouting (PHS) is the premature germination of seeds, which is often caused by late‐season rains after seeds reach physiological maturity. PHS negatively impacts grain yield and end‐use quality. Previous studies in spring bread wheat (Triticum aestivum) and durum wheat (Triticum turgidum) have identified that some mutations in the mother of FT and TFL1 gene (MFT) coding sequence decrease seed dormancy and increase wheat PHS.FindingsHere, we report two novel alleles for the MFT‐A and two novel alleles for the MFT‐B1 homologs in spring bread wheat and durum wheat.ConclusionsA haplotype analysis suggests that TaMFT‐3A1b (OQ729929), TaMFT‐3B1b (OQ729932) and TdMFT‐3B1b (OQ729937) increase PHS susceptibility. It is expected that functional copies of MFT promote seed dormancy. Variant analysis of the novel MFT‐A and MFT‐B1 alleles in both spring and durum wheat suggest impairment of protein function, therefore a negative impact on seed dormancy.Significance and Novelty: Previously unassessed durum wheat varieties were examined for PHS susceptibility. The information in this study can serve as a resource for spring and durum wheat breeders to make selections for alleles of MFT that impact susceptibility to PHS.

Anatomical and Ionomics Investigation of Bread Wheat (Triticum aestivum L.) to Decipher Tolerance Mechanisms Under Arsenic Stress

Anatomical and Ionomics Investigation of Bread Wheat (Triticum aestivum L.) to Decipher Tolerance Mechanisms Under Arsenic Stress

Composition of high-molecular-weight glutenin subunits and gluten quality in wheat lines with alien genetic material

Background. High-molecular-weight glutenin subunits (HMW-GSs) make the greatest contribution to the formation of baking properties in bread wheat (Triticum aestivum L.). Glutenin polymorphism of bread wheat relatives is significantly richer than in cultivated varieties. The objective of this work was to identify the HMW-GS composition and assess the gluten quality of bread wheat lines with introgressions of alien genetic material.Materials and methods. We studied the parental varieties of spring bread wheat, accessions of the tetraploid and hexaploid Triticum L. species, and 19 introgressive lines produced with their participation. Glutenins were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis and HMW-GSs were identified using the Payne nomenclature system. Gluten quality was determined in accordance with GOST 13586.1-68 (the 2017–2019 and 2021–2022 growing seasons). Data processing was performed using the Statistica 10.0 and MS Excel software packages.Results and conclusion. HMW-GSs uncharacteristic of T. aestivum cultivars were identified in the studied accessions of T. dicoccoides (Körn. ex Aschers. et Graebn.) Schweinf., T. spelta L., and T. kiharae Dorof. et Migusch. These HMW-GSs are of interest for enriching the wheat gene pool. HMW-GSs of related species were found in 10 out of 19 introgressive lines. A five-year observation period revealed that wheat relatives on average significantly exceeded common wheat cultivars in gluten quality, and introgressive lines did not differ significantly from the parental genotypes. Lines with high rheological properties of gluten had, as a rule, HMW-GSs of related species in their composition.

Proteomics profiling reveals the detoxification and tolerance behavior of two bread wheat (Triticum aestivum L.) varieties under arsenate stress

Arsenic (As) contaminated irrigation water caused a significant buildup of its level in the agricultural soil and edible tissues of wheat. High levels of As negatively impact grain quality, wheat yield, and human health consequently. It is still unknown how wheat varieties respond to As stress at the proteomic level. Therefore, the present study aimed to deliver mechanistic details regarding the role of proteins in tolerance mechanism against As stress. Two wheat varieties (BARANI-70 and NARC-2009) were exposed to arsenate treatment (200µM) in a hydroponic experiment to evaluate the impacts of arsenic stress using proteomics. Roots of both varieties were used for protein extraction, digestion, and LC-MS/MS analysis to identify differentially abundant proteins (DAPs). Furthermore, various bioinformatic tools were used to study subcellular localization, functional categories, and pathway analysis. The findings identified 67 DAPs in BARANI-70 (up-regulated=56; down-regulated=11) and 89 DAPs in NARC-2009 (up-regulated=34; down-regulated=55). Subcellular localization revealed significant up-regulation of DAPs in mitochondria and chloroplast for BARANI-70 but down-regulation in NARC-2009 under As stress. Functional analysis revealed significant upregulation of DAPs for glutathione, peroxidase, glutathione peroxidase, lactoylglutathione lyase, and glutathione-s-transferase in BARANI-70. Pathway analysis showed regulation of DAPs involved in tetrapyrrole biosynthesis and glycolysis-TCA particularly in BARANI-70 compared to NARC-2009. Furthermore, BARANI-70 showed better growth response under As stress compared to NARC-2009. Thus, better synthesis of stress-responsive DAPs and important pathways in BARANI-70 contributed towards its tolerance against As stress. The present research supports the use of tolerant varieties and identified protein biomarkers to enhance crop resilience against As stress.

Selectivity of the Premixtures Flufenacet, Diflufenican and Flufenacet, Diflufenican, Metribuzin on Bread Wheat (Triticum aestivum L.) and Barley (Hordeum vulgare L.) and Efficacy on ALS/ACCase-Resistant Populations of Lolium rigidum Gaudin

The premixtures flufenacet plus diflufenican and flufenacet plus diflufenican plus metribuzin are two herbicides recently registered in Greece for weed control in bread wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) with application early post-emergence to the crop (1st–3rd leaf growth stage). To evaluate the selectivity of these new herbicides, pot experiments were conducted by applying flufenacet plus diflufenican at 240 + 120 g ai ha−1 and flufenacet plus diflufenican plus metribuzin at 119.7 + 119.7 + 44.8 g ai ha−1 to bread wheat and barley, at 1st (BBCH-11), 2nd (BBCH-12) and 3rd (BBCH-13) leaf growth stage. The efficacy of the herbicides at the above-mentioned rates in pre-emergence application was also tested on three ALS/ACCase herbicide-resistant populations of Lolium rigidum Gaudin in comparison with the pre-emergence herbicides prosulfocarb and chlorotoluron plus diflufenican at 3200 g ai ha−1 and 1380 + 92 g ai ha−1, respectively. The results revealed decreased selectivity of both premixtures when applied at BBCH-11 for both winter cereals, with flufenacet plus diflufenican being less selective compared to flufenacet plus diflufenican plus metribuzin. Both herbicides highly controlled the three herbicide-resistant L. rigidum populations. The results indicated that both premixtures are effective chemical options for the management of herbicide resistant L. rigidum. To ensure crop safety and optimize efficacy, application at BBCH-12 is recommended.

Bread wheat (Triticum aestivum L.) fungal and mycotoxin contamination control enhanced by a dual-frequency cold plasma

In this study a dual-frequency plasma generated at 1 Pa in synthetic air was investigated for the inactivation of fungal contaminants and the reduction of mycotoxin content in bread wheat grains. This coupled device increased the rates of emitted species (RONS and UV) and provided a relative control of charged particles flux-energy balance (ne ≃ 1016 m−3 − ɛi ≃ 8 eV). This plasma-based decontamination process allowed 1.5 log of reduction onto wheat grains exposed 90 min to plasma and a degradation of more than 90 % for the deoxynivalenol mycotoxin content of a glass carrier after 5 min plasma exposure.

Assessment of the salt tolerance of diverse bread wheat (Triticum aestivum L.) genotypes during the early growth stage under hydroponic culture conditions

ObjectivesSoil salinity affects the growth of crop plants, leading to reduced productivity, and is a major challenge for wheat production worldwide. Various adaptations and mitigation approaches in combination with tolerant wheat genotypes can be useful for the sustainability of crop production in saline environments. However, the development of salt-tolerant wheat genotypes is one of the best and most efficient solutions for obtaining desirable yields. Considering these issues, an investigation was carried out under hydroponic nutrient culture conditions to assess the genetic variability and selection of salt-tolerant wheat genotypes by categorizing inequitable morphophysiological and genetic variability as well as multivariate analysis. MethodsTo meet the objectives of this study, 100 wheat genotypes were tested hydroponically in 0 (control) and 15 dS m−1 salt solutions. ConclusionFor all the wheat genotypes grown under saline conditions, the shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), total fresh weight (TFW), shoot dry weight (SDW), root dry weight (RDW), and total dry weight (TDW) decreased significantly. Furthermore, significant variation was observed among the genotypes in terms of their characteristics only under saline conditions. In the case of genetic diversity analysis, a high genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), genetic advance in the percentage of the mean (GAM) and high heritability (h2b) were recorded for all tested wheat genotypes based on the SDW, RDW and TDW. Correlation analysis for both genotypic and phenotypic relationships revealed strong positive correlations for TDW, SDW, TFW and SFW. Principal component analysis (PCA) revealed that TDW, TFW, SDW, and SFW were the most discriminative variables for the wheat genotypes, which was confirmed by discriminant function analysis (DFA). PCA-biplot analysis also revealed significant positive correlations between SDW and SFW and between TDW and TFW. Hierarchical cluster analysis was performed for ten clusters based on the relative performance of the genotypes, where the genotypes were characterized into salt-tolerant, medium-salt-tolerant, medium-salt-susceptible and salt-susceptible groups. Among the genotypes, G11, G25 and G29 under cluster VII were categorized as salt tolerant based on their outstanding performance in terms of characteristics only under saline conditions. D2 analysis proved that the wheat genotypes of this cluster were highly divergent from the other cluster genotypes; as a result, these genotypes might be utilized as parents in the development of salt-tolerant wheat genotypes. The current study concluded that SDW and TDW could be employed as criteria for selecting and defining salt-tolerant genotypes during the early growth stage of wheat.

Evaluation of elite spring wheat genotypes for grain yield and other agronomic attributes in hills of Sudurpaschim Province, Nepal

Selection and release of high yielding and disease resistant varieties is the cost effective and ecologically sound approach for increasing the production and productivity of agricultural crop in Nepal. Twenty-two advanced bread wheat (Triticum aestivum L.) genotypes including commercial check variety "Sorgadwari", newly released check variety "Khumal Shakti" and Local Check variety " Jhadde" were evaluated under irrigated conditions at Gokuleshwor Agriculture and Animal Science College (GAASC), Baitadi, Nepal during 2022/2023. This study was carried out for the identification of high yielding genotypes under irrigated condition in western hills. The experiment was conducted in Alpha lattice design with two replications. The highly significant difference (p<0.01) among the genotypes was found for most of the traits viz., days to heading, days to anthesis, days to maturity, plant height, spikes per square meter, number of grains per spike, grain weight per spike, flag leaf area, thousand kernel weight, biomass yield and grain yield and non-significant difference for spike length. The mean grain yield ranged from 1908 to 4146 kg/ha with grand mean of 2766 kg/ha. The highest grain yield was produced by genotype NL 1474 (4146 kg/ha) which was followed by NL 1475 (3994 kg/ha), NL1597 (3536 kg/ha) and NL 1590 (3070 kg/ha). The check variety Sorgadwari and Khumal Shakti produced 3480 and 3070 kg/ha respectively while the local check variety Jhadde produced 2655 kg/ha. Similarly, highest TKW was produced by NL 1487 (68.5 g) followed by BL 5148 (67.2 g) and WK 3730 (66.3 g). The correlation analysis revealed that grain yield showed highly significant positive correlation with biomass yield (0.90**) and number of grains per spike (0.6**), spikes per square meter (0.7**), plant height (0.5**) and non-significant positive correlation with spike length (0.21) and grain weight per spike (0.1) and non-significant negative correlation with days to heading (-0.2) and days to maturity (-0.2). Cluster analysis revealed that Cluster III consists of 4 genotypes namely NL 1474, NL 1475, NL 1597 and Sorgadwari. This cluster represent with highest grain yield, number of spikes per meter square, number of grains per spike and grain weight per spike. Among the tested genotypes, NL 1474, NL 1475, NL 1597 and NL 1590 were found superior for grain yield and yield-related traits in comparison to three checks and could be recommended for hills of Sudurpaschim province after further testing in multi-environment and in farmer's field.

Arbuscular mycorrhizal fungi impact on yield attributes, protein quantity and quality in bread wheat (Triticum aestivum L.) grown under drought stress

Drought is increasingly becoming a production constraint in wheat world-wide. Arbuscular mycorrhizal fungi (AMF)-bread wheat symbiosis has been shown to improve the tolerance under drought stress. The objective of this study was to determine the effects of AMF inoculation on yield attributes (spike number per plant, spike weight per plant, number of grains per spike, grain weight per spike and 1000 grain weight) and protein quantity and quality in two bread wheat cultivars (PAN3497 and SST806) grown under drought stress. Plant growth was significantly reduced due to drought stress in both cultivars. Shoot dry weight was significantly increased (23%) due to AMF inoculation in SST806. AMF inoculation caused a further significant increase of protein content in both cultivars (10.70% and 13.42% in PAN3497 and SST806, respectively). Low molecular weight (LMW) glutenin was significantly decreased in PAN3497 under drought stress. However, the monomeric proteins were significantly increased by drought and/or a combination of drought and AMF inoculation in both cultivars. In cultivar SST806, significant reduction of polymeric protein was observed due to application of both AMF (6%) and a combination of AMF with drought stress (4%). Regarding the two-dimensional separation of the gluten proteins, drought had the largest effect on protein spots, with AMF causing up-regulation of only some spots. SST806 was generally more drought tolerant than PAN3497.

Estimate the Genetic Diversity with PCA in Bread Wheat (Triticum aestivum L.)

The present investigation was carried out on bread wheat (Triticum aestivum L.) crop during rabi season with the aims of analysis of genetic diversity with the help of principle component analysis. The experimental sample size included 80 genotypes, in an augmented block design with three replications. Observation was based upon twenty-six quantitative characteristics. For all characteristics Cluster I had highest number of genotypes (28) followed by cluster II (5), cluster IV, cluster V and cluster VI had presented (4), cluster VII and VIII (3), cluster III, cluster IX, cluster X, cluster XI and cluster XII (2) whereas cluster had presented one entry in each group. The minimum intra cluster distance (0.00) was found for XIII to XXXI and maximum was found for cluster XII (2.10). The maximum inter-cluster distance was found between cluster XX to XXVII (11.08). The minimum inter- cluster D2 value found in case of cluster IV to XVI and XXX to XXXI (2.12). Cluster XVIII showed earliest mean value for day to 50 per cent flowering (75.24 day) and most important character maximum mean value for yield per plot (536.13). Principal component analysis (PCA) indicated that the five principal components (PC1 to PC5) showed 50.37 per cent of the total variability. The five different groups positive maximum variable loaded component PC I for grain yield per plant (23.2542), PC II flag leave area (19.4005), PC III for peduncle length (23.9893), PC IV grain length /width ratio (21.0627), PC V for physiological maturity (16.7492). As a result of the foregoing data, it is possible to conclude that there is great potential for effective crop modification for improved yield and yield-attributing traits in present wheat germplasm.

D genome acquisition and breeding have had a significant impact on interaction of wheat with ACC deaminase producers in soil or ACC deaminase potential activity in the rhizosphere

Rhizosphere functioning depends on plant traits, but the underlying genotypic properties are poorly understood. Wheat has undergone several domestication events combined with genomic hybridization, including the acquisition by Triticum dicoccon (AABB genome) of the D genome from Aegilops tauschii, resulting into bread wheat Triticum aestivum (AABBDD genome). The D genome is likely to modulate the functioning of beneficial wheat-microbe interactions, but data are needed to substantiate this. Here, we tested the hypothesis that genome D is important for soil interactions of wheat with 1-aminocyclopropane-1-carboxylate (ACC) deaminase producers, a key microbial functional group that enhances plant performance by fine-tuning ethylene metabolism in roots. A range of wheat lines from T. aestivum (AABBDD), T. diccocon (AABB) and Ae. tauschii (DD) were compared based on abundance (qPCR on acdS gene marker), diversity (Illumina MiSeq) and potential ACC deaminase activity (colorimetric assays) of ACC deaminase producers in the rhizosphere. Results showed that the abundance of ACC deaminase producers was lower for D-genome wheats than D-negative T. dicoccon at 40 days, but ACC deaminase potential activity in the rhizosphere was lower for D-genome Ae. tauschii and T. aestivum landraces than T. aestivum cultivars (recent and old), while D-negative T. dicoccon was in between. Rhizosphere community structure of Ae. tauschii and T. dicoccon differed from that of T. aestivum, and differences occurred also between various genotype categories of T. aestivum. Overall, the acquisition of the D genome has had a negative impact on the ability of wheat to recruit ACC deaminase producers in soil, but bread wheats resulting from recent breeding displayed improved ACC deaminase activity in the rhizosphere.

Dissecting the molecular basis of spike traits by integrating gene regulatory networks and genetic variation in wheat

Spike architecture influences both grain weight and grain number per spike, which are the two major components of grain yield in bread wheat (Triticum aestivum L.). However, the complex wheat genome and the influence of various environmental factors pose challenges in mapping the causal genes that affect spike traits. Here, we systematically identified genes involved in spike trait formation by integrating information on genomic variation and gene regulatory networks controlling young spike development in wheat. We identified 170 loci that are responsible for variations in spike length, spikelet number per spike, and grain number per spike through genome-wide association study and meta-QTL analyses. We constructed gene regulatory networks for young inflorescences at the double ridge stage and the floret primordium stage, in which the spikelet meristem and the floret meristem are predominant, respectively, by integrating transcriptome, histone modification, chromatin accessibility, eQTL, and protein–protein interactome data. From these networks, we identified 169 hub genes located in 76 of the 170 QTL regions whose polymorphisms are significantly associated with variation in spike traits. The functions of TaZF-B1, VRT-B2, and TaSPL15-A/D in establishment of wheat spike architecture were verified. This study provides valuable molecular resources for understanding spike traits and demonstrates that combining genetic analysis and developmental regulatory networks is a robust approach for dissection of complex traits.

A new winter wheat genetic resource harbors untapped diversity from synthetic hexaploid wheat

Key messageThe NIAB_WW_SHW_NAM population, a large nested association mapping panel, is a useful resource for mapping QTL from synthetic hexaploid wheat that can improve modern elite wheat cultivars.The allelic richness harbored in progenitors of hexaploid bread wheat (Triticum aestivum L.) is a useful resource for addressing the genetic diversity bottleneck in modern cultivars. Synthetic hexaploid wheat (SHW) is created through resynthesis of the hybridisation events between the tetraploid (Triticum turgidum subsp. durum Desf.) and diploid (Aegilops tauschii Coss.) bread wheat progenitors. We developed a large and diverse winter wheat nested association mapping (NAM) population (termed the NIAB_WW_SHW_NAM) consisting of 3241 genotypes derived from 54 nested back-cross 1 (BC1) populations, each formed via back-crossing a different primary SHW into the UK winter wheat cultivar ‘Robigus’. The primary SHW lines were created using 15 T. durum donors and 47 Ae. tauschii accessions that spanned the lineages and geographical range of the species. Primary SHW parents were typically earlier flowering, taller and showed better resistance to yellow rust infection (Yr) than ‘Robigus’. The NIAB_WW_SHW_NAM population was genotyped using a single nucleotide polymorphism (SNP) array and 27 quantitative trait loci (QTLs) were detected for flowering time, plant height and Yr resistance. Across multiple field trials, a QTL for Yr resistance was found on chromosome 4D that corresponded to the Yr28 resistance gene previously reported in other SHW lines. These results demonstrate the value of the NIAB_WW_SHW_NAM population for genetic mapping and provide the first evidence of Yr28 working in current UK environments and genetic backgrounds. These examples, coupled with the evidence of commercial wheat breeders selecting promising genotypes, highlight the potential value of the NIAB_WW_SHW_NAM to variety improvement.

Unravelling the novel genetic diversity and marker-trait associations of corn leaf aphid resistance in wheat using microsatellite markers.

The study was conducted to identify novel simple sequence repeat (SSR) markers associated with resistance to corn aphid (CLA), Rhopalosiphum maidis L. in 48 selected bread wheat (Triticum aestivum L.) and wild wheat (Aegilops spp. & T. dicoccoides) genotypes during two consecutive cropping seasons (2018-19 and 2019-20). A total of 51 polymorphic markers containing 143 alleles were used for the analysis. The frequency of the major allele ranged from 0.552 (Xgwm113) to 0.938 (Xcfd45, Xgwm194 and Xgwm526), with a mean of 0.731. Gene diversity ranged from 0.116 (Xgwm526) to 0.489 (Xgwm113), with a mean of 0.354. The polymorphic information content (PIC) value for the SSR markers ranged from 0.107 (Xgwm526) to 0.370 (Xgwm113) with a mean of 0.282. The results of the STRUCTURE analysis revealed the presence of four main subgroups in the populations. Analysis of molecular variance (AMOVA) showed that the between-group difference was around 37 per cent of the total variation contributed to the diversity by the whole germplasm, while 63 per cent of the variation was attributed between individuals within the group. A general linear model (GLM) was used to identify marker-trait associations, which detected a total of 23 and 27 significant new marker-trait associations (MTAs) at the p < 0.01 significance level during the 2018-19 and 2019-20 crop seasons, respectively. The findings of this study have important implications for the identification of molecular markers associated with CLA resistance. These markers can increase the accuracy and efficiency of aphid-resistant germplasm selection, ultimately facilitating the transfer of resistance traits to desirable wheat genotypes.

Phytotoxic Ozone Dose-Response Relationships for Durum Wheat (Triticum durum, Desf.).

Ozone (O3) pollution poses a significant threat to global crop productivity, particularly for wheat, one of the most important staple foods. While bread wheat (Triticum aestivum) is unequivocally considered highly sensitive to O3, durum wheat (Triticum durum) was often found to be more tolerant. This study investigated the O3 dose-response relationships for durum wheat in the Mediterranean region, focusing mainly on grain yield losses, and utilizing the phytotoxic ozone dose (POD) metric to describe the intensity of the stressor. The results from two experiments with Open-Top Chambers performed in 2013 and 2014 on two relatively sensitive durum wheat cultivars confirmed that this wheat species is far more tolerant than bread wheat. The use of a local parameterization of a stomatal conductance model based on field measurements did not significantly improve the dose-response relationships obtained in comparison to the generic parameterization suggested by the Mapping Manual of the United Nations Economic Commission for Europe (UNECE). The POD6 critical level of 5 mmolO3 m-2 for 5% grain yield loss was remarkably higher than the one established for bread wheat with analogous experiments, highlighting that O3 risk assessments based on bread wheat may largely overestimate the damage in the Mediterranean region where durum wheat cultivation prevails.

Deciphering induced variability, character association and multivariate analysis utilizing gamma rays and ethyl methanesulfonate in bread wheat (Triticum aestivum L.) genotypes with differential grain texture

Purpose Sustainable wheat production and higher genetic gains can be realized by broadening the genetic base and improving the well adapted varieties. In the present study, a multi-year experiment involving induced mutagenesis was conducted to create genetic variation, assess trait associations and genetic divergence in four wheat varieties with differential grain texture treated with six doses of gamma rays and ethyl methane sulfonate using ten agro-morphological traits. Materials and methods Healthy selfed seeds of four bread wheat varieties with differential texture were irradiated using six doses ranging from 175 Gy-300 Gy of gamma rays (Co60: BARC, Mumbai) and six concentrations of ethyl methanesulfonate (0.3–1.3%) (Sigma-Aldrich, Bangalore, India) to evaluate variability, character association and degree of genetic diversity induced among the mutagenic treatments of wheat varieties with differential grain texture. Results Significant inter-population differences were observed for almost all the traits. The sample mean of twelve mutant populations in each of the cultivar exhibited superior quantitative phenotypic traits and increased values of the genetic parameters. Based on association and variability studies, plant height, spike length, grain filling period, biological yield per plant and harvest index can be used as early generation criteria for maximum genetic improvement. Multivariate studies indicated the contribution of various traits towards divergence and indicated the efficiency of mutagens in generating variability. Gamma-irradiation dosages between 200–250 Gy and 0.5–1.1% EMS for soft-textured varieties, whereas doses between 225–275 Gy and 0.5–0.9% EMS were found to be most potent for semi-hard-textured varieties. Conclusions Assessment of mutagen sensitivity showed that semi-hard wheat varieties were responsive to both mutagens, particularly EMS and generated higher variability and divergence than the soft textured varieties. Hence, gamma rays were proved to be more effective in generating higher variability than ethyl methanesulfonate. A total of 117 putative mutants were identified with desirable agro-morphological attributes. Among these, mutants with higher inter-cluster distance can be used as parents in hybridization programs and serve as important genetic resources in future wheat improvement programs.