Heat stress tolerance in plants is a complex trait controlled by multiple genes of minor effect which are influenced by the environment and this makes breeding and selection complicated. Emmer wheat (Triticum dicoccon Schrank) carries valuable diversity that can be used to improve the heat tolerance of modern bread wheat. A diverse set of emmer-based genotypes was developed by crossing emmer wheat with hexaploid wheat. These materials, along with their hexaploid recurrent parents and commercial cultivars, were evaluated at optimum (E1) and heat stressed (E2) sowing times in the field for three consecutive years (2014-2016). The material was genotyped using the Infinium iSelect SNP 90K SNP Assay. The phenotypic data were combined across years within each sowing time and best linear unbiased estimators calculated for each genotype in each environment. These estimates were used for GWAS analysis. Significant phenotypic and genotypic variation was observed for all traits. A total of 125 and 142 marker-trait associations (MTAs) were identified in E1 and E2, respectively. The highest number of MTAs were observed on the A genome (106), followed by the B (105) and D (56) genomes. MTAs with pleiotropic effects within and across the environments were observed. Many of the MTAs found were reported previously for various traits, and a few significant MTAs under heat stress were new and linked to emmer genome. Genomic regions identified on chromosomes 2B and 3A had a significant positive impact on grain yield under stress with a 7% allelic effect. Genomic regions on chromosomes 1A and 4B contributed 11% and 9% of the variation for thousand kernel weight (TKW) under heat stress respectively. Following fine mapping, these regions could be used for marker-assisted selection to improve heat tolerance in wheat.

植物的热胁迫耐受性是一个复杂的性状，由多个效应较小的基因控制，且受环境影响，这使得育种和选择变得复杂。二粒小麦（Triticum dicoccon Schrank）具有宝贵的多样性，可用于提高现代面包小麦的耐热性。通过将二粒小麦与六倍体小麦杂交，开发了一组多样化的基于二粒小麦的基因型。这些材料及其六倍体轮回亲本和商业品种，连续三年（2014-2016）在田间的最佳（E1）和热应激（E2）播种时间进行了评估。使用 Infinium iSelect SNP 90K SNP Assay 对材料进行基因分型。将每个播种时间内的表型数据进行跨年组合，并为每个环境中的每个基因型计算最佳线性无偏估计量。这些估计值用于 GWAS 分析。所有性状均观察到显着的表型和基因型变异。在 E1 和 E2 中分别鉴定出总共 125 个和 142 个标记-性状关联 (MTA)。在 A 基因组上观察到的 MTA 数量最多 (106)，其次是 B (105) 和 D (56) 基因组。观察到在环境内部和环境之间具有多效性的 MTA。之前发现的许多 MTA 具有各种性状，并且一些热应激下的重要 MTA 是新的且与二粒小麦基因组相关。2B 和 3A 号染色体上鉴定的基因组区域对胁迫下的谷物产量具有显着的积极影响，等位基因效应为 7%。1A 和 4B 号染色体上的基因组区域分别对热应激下千粒重 (TKW) 的变异贡献了 11% 和 9%。经过精细绘图后，这些区域可用于标记辅助选择，以提高小麦的耐热性。