Genetic improvement along with widened crop base necessitates for the detailed understanding of the genetic diversity and population structure in wheat. The present investigation reports the discovery of a total of 182 alleles by assaying 52 simple sequence repeats (SSRs) on 40 genotypes of bread wheat. Unweighted neighbour-joining method grouped these genotypes into two main clusters. Highly heat tolerant and intermediate tolerant cultivars were grouped in the same cluster, whereas remaining genotypes, particularly sensitive ones, were assigned different cluster. Similarly, the entire population was structured into two sub-populations (K = 2), closely corresponding with the other distance-based clustering patterns. The marker-trait association was discovered for four important physiological parameters, viz. canopy temperature depression, membrane thermostability index (MSI), normalized difference vegetation index and heat susceptibility index, indicating for heat stress (HS) tolerance in wheat. Both general and mixed linear models of association studies during 2017 and 2018, revealed the association of SSR markers, wmc222 (17.60%, PV) and gwm34 (20.70%, PV) with the mean phenotypic value of MSI. Likewise, SSR markers barc183, gwm75, gwm11 and cfd7 revealed a unique relationship with four selected physiological traits. Candidate genes discovered using in silico tools had nine SSR markers within the genic regions reported to play a role in heat and drought stress responses in plants. The information generated about these genic regions may be explored further in expression studies in-vivo to impart HS tolerance in bread wheat.

中文翻译：

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面包小麦 (Triticum aestivum L. em Thell) 的群体结构、标记-性状关联和候选基因鉴定最终热应激相关性状

随着作物基础的扩大，遗传改良需要详细了解小麦的遗传多样性和种群结构。本研究报告通过对 40 种面包小麦基因型的 52 个简单序列重复 (SSR) 进行分析，发现了总共 182 个等位基因。未加权邻接法将这些基因型分为两个主要集群。高耐热和中等耐热品种被归为同一簇，而其余基因型，特别是敏感基因型，被分配到不同的簇中。类似地，整个种群被分为两个亚种群（ķ= 2)，与其他基于距离的聚类模式密切对应。发现了四个重要生理参数的标记-性状关联，即。冠层温度下降，膜热稳定性指数（MSI），归一化植被指数和热敏感性指数，表明小麦对热胁迫（HS）的耐受性。2017 年和 2018 年关联研究的一般和混合线性模型都揭示了 SSR 标记的关联，wmc222（17.60%，现值）和gwm34(20.70%, PV) 与 MSI 的平均表型值。同样，SSR 标记barc183、gwm75、gwm11和cfd7揭示了与四种选定的生理特征的独特关系。使用发现的候选基因计算机工具在基因区域内有九个 SSR 标记，据报道它们在植物的热和干旱胁迫反应中发挥作用。可以在表达研究中进一步探索关于这些基因区域产生的信息体内赋予面包小麦对 HS 的耐受性。