State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China; Pioneering Innovation Center for Wheat Stress Tolerance Improvement, State Key Laboratory of Crop Stress Biology for Arid Areas, Yangling, Shaanxi 712100, China.
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
Mol Plant. 2022 Feb 7;15(2):276-292. doi: 10.1016/j.molp.2021.11.007. Epub 2021 Nov 15.
Drought is a major environmental factor limiting wheat production worldwide, and developing drought-tolerant cultivars is a central challenge for wheat breeders globally. Therefore, it is important to identify genetic components determining drought tolerance in wheat. In this study, we identified a wheat NAC gene (TaNAC071-A) that is tightly associated with drought tolerance by a genome-wide association study. Knockdown of TaNAC071-A in wheat attenuated plant drought tolerance, whereas its overexpression significantly enhanced drought tolerance through improved water-use efficiency and increased expression of stress-responsive genes. This heightened water-saving mechanism mitigated the yield loss caused by water deficit. Further candidate gene association analysis showed that a 108-bp insertion in the promoter of TaNAC071-A alters its expression level and contributes to variation in drought tolerance among wheat accessions. This insertion contains two MYB cis-regulatory elements (CREs) that can be directly bound by the MYB transcription activator, TaMYBL1, thereby leading to increased TaNAC071-A expression and plant drought tolerance. Importantly, introgression of this 108-bp insertion allele, TaNAC071-A, into drought-sensitive cultivars could improve their drought tolerance, demonstrating that it is a valuable genetic resource for wheat breeding. Taken together, our findings highlight a major breakthrough in determining the genetic basis underlying phenotypic variation in wheat drought tolerance and showcase the potential of exploiting CRE-containing indels for improving important agronomical traits.
干旱是全球范围内限制小麦生产的主要环境因素，培育耐旱品种是全球小麦育种者面临的主要挑战。因此，确定决定小麦耐旱性的遗传成分非常重要。在这项研究中，我们通过全基因组关联研究鉴定了一个与耐旱性紧密相关的小麦 NAC 基因（TaNAC071-A）。小麦中 TaNAC071-A 的敲低削弱了植物的耐旱性，而其过表达通过提高水分利用效率和增加应激响应基因的表达显著增强了耐旱性。这种节水机制减轻了水分亏缺引起的产量损失。进一步的候选基因关联分析表明，TaNAC071-A 启动子中的 108bp 插入改变了其表达水平，并导致小麦品系间耐旱性的变异。该插入包含两个 MYB 顺式调控元件（CREs），可以直接被 MYB 转录激活因子 TaMYBL1 结合，从而导致 TaNAC071-A 的表达增加和植物耐旱性增强。重要的是，将这个 108bp 插入等位基因 TaNAC071-A 导入到耐旱性敏感的品种中可以提高它们的耐旱性，表明它是小麦育种的有价值的遗传资源。总之，我们的研究结果强调了确定小麦耐旱性表型变异遗传基础的重大突破，并展示了利用含有 CRE 的插入缺失来改良重要农艺性状的潜力。
