Drought is a major environmental factor limiting wheat production worldwide. However, the genetic components underlying wheat drought tolerance are largely unknown. Here, we identify a DREB transcription factor gene (TaDTG6-B) by genome-wide association study that is tightly associated with drought tolerance in wheat. Candidate gene association analysis revealed that a 26-bp deletion in the TaDTG6-B coding region induces a gain-of-function for TaDTG6-BDel574, which exhibits stronger transcriptional activation, protein interactions, and binding activity to dehydration-responsive elements (DRE)/CRT cis-elements than the TaDTG6-BIn574 encoded by the allele lacking the deletion, thus conferring greater drought tolerance in wheat seedlings harboring this variant. Knockdown of TaDTG6-BDel574 transcripts attenuated drought tolerance in transgenic wheat, whereas its overexpression resulted in enhanced drought tolerance without accompanying phenotypic abnormalities. Furthermore, the introgression of the TaDTG6-BDel574 elite allele into drought-sensitive cultivars improved their drought tolerance, thus providing a valuable genetic resource for wheat breeding. We also identified 268 putative target genes that are directly bound and transcriptionally regulated by TaDTG6-BDel574. Further analysis showed that TaDTG6-BDel574 positively regulates TaPIF1 transcription to enhance wheat drought tolerance. These results describe the genetic basis and accompanying mechanism driving phenotypic variation in wheat drought tolerance, and provide a novel genetic resource for crop breeding programs.

中文翻译：

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DREB 转录因子基因的功能获得等位基因改善了小麦的耐旱性。

干旱是限制全球小麦产量的主要环境因素。然而，小麦耐旱性背后的遗传成分在很大程度上尚不清楚。在这里，我们通过全基因组关联研究鉴定了一个与小麦耐旱性密切相关的 DREB 转录因子基因（TaDTG6-B）。候选基因关联分析显示，TaDTG6-B 编码区的 26 bp 缺失可诱导 TaDTG6-BDel574 获得功能，表现出更强的转录激活、蛋白质相互作用以及与脱水响应元件 (DRE) 的结合活性/CRT 顺式元件比缺乏缺失的等位基因编码的 TaDTG6-BIn574 具有更多的顺式元件，因此赋予携带该变体的小麦幼苗更强的耐旱性。TaDTG6-BDel574 转录物的敲低减弱了转基因小麦的耐旱性，而其过表达则导致耐旱性增强而不伴随表型异常。此外，TaDTG6-BDel574优良等位基因渗入干旱敏感品种，提高了其耐旱性，从而为小麦育种提供了宝贵的遗传资源。我们还鉴定了 268 个推定的靶基因，它们直接与 TaDTG6-BDel574 结合并进行转录调控。进一步分析表明，TaDTG6-BDel574正向调控TaPIF1转录，增强小麦的耐旱性。这些结果描述了小麦耐旱性表型变异的遗传基础和伴随机制，并为作物育种计划提供了新的遗传资源。