Drought is one of the most important abiotic stresses affecting wheat growth. Evaluation of a structured population over seasons and moisture conditions allow for the detection of genes involved in drought tolerance. The aims of the present study were to analyze root and agronomic characters under two moisture conditions and identify marker-trait associations in 220 doubled haploid (DH) lines developed from a cross between Kukri and RAC875. The DH lines were evaluated for grain yield (GY) and several root and agronomic traits in four trials included drought stress experiments (DrExp) at heading stage and well-watered conditions (NExp) throughout the growth season in 2015 and 2016. A linkage map comprised of 1333 SSR, DArT and SNP markers were used for the analysis of quantitative traits loci (QTL). The results of QTL analysis showed that four and seven QTL were identified for root traits in the DrExp 15 and DrExp 16 trials, respectively. The results of QTL analysis suggested that the contribution of the three genomes to drought tolerance was not similar. The Q.Rdrw-4A QTL explained 7.05 and 10.43% of root dry weight variances in the DrExp15 and DrExp 16 trials, respectively. A QTL mapped on the D_GA8KES401CIKOJ–160-BS00067285_51 marker interval for root length was co-localized with a QTL for grain weight per spike under drought conditions. A year-specific main effect QTL and several stable epistatic QTL were identified for days to heading in the DrExp and NExp experiments, respectively. Search for gene annotation in the wheat genome showed that the position of this QTL was overlapped with the tRNA, sRNA and protein-encoding genes. Three QTL were identified for GY of which the Q.Gy-2D QTL identified in NExp 16 whilst Q.Gy-3D and an epistatic effect detected in drought conditions. The common QTL identified allows for increasing selection efficiency and the fine-tuning of root and agronomic traits for sustainable wheat production under water deficit conditions.

中文翻译：

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干旱胁迫条件下Kukri/RAC875小麦（Triticum aestivum L.）群体农艺和根系性状的QTL定位

干旱是影响小麦生长的最重要的非生物胁迫之一。在季节和湿度条件下对结构化种群进行评估可以检测与耐旱性有关的基因。本研究的目的是分析两种水分条件下的根和农艺性状，并确定由 Kukri 和 RAC875 杂交产生的 220 个双单倍体 (DH) 品系中的标记-性状关联。在四项试验中对 DH 品系的谷物产量 (GY) 和几个根系和农艺性状进行了评估，包括抽穗期的干旱胁迫试验 (DrExp) 和 2015 年和 2016 年整个生长季节的良好浇水条件 (NExp)。 连锁图由1333个SSR、DArT和SNP标记组成，用于数量性状位点（QTL）分析。QTL分析结果表明，在DrExp 15和DrExp 16试验中分别鉴定出4个和7个根性状QTL。QTL分析结果表明，三个基因组对耐旱性的贡献不相似。Q.Rdrw-4A QTL 分别解释了 DrExp15 和 DrExp 16 试验中根干重差异的 7.05% 和 10.43%。定位在 D_GA8KES401CIKOJ–160-BS00067285_51 标记区间的根长 QTL 与干旱条件下每个穗粒重的 QTL 共定位。分别在 DrExp 和 NExp 实验中确定了一个年份特定的主效应 QTL 和几个稳定的上位 QTL。在小麦基因组中寻找基因注释表明该QTL的位置与tRNA、sRNA和蛋白质编码基因重叠。鉴定了 GY 的三个 QTL，其中 Q.Gy-2D QTL 在 NExp 16 中鉴定，而 Q.Gy-3D 和在干旱条件下检测到的上位效应。确定的共同 QTL 可以提高选择效率并微调根系和农艺性状，以在缺水条件下实现可持续的小麦生产。