Variation in cis-regulation of a NAC transcription factor contributes to tolerance in wheat

Drought is a major environmental factor limiting wheat production worldwide, and developing droughttolerant 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-AIn-693, 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.

Automated summary

Drought is a major limitation to wheat production worldwide, and understanding the genetic components determining drought tolerance is crucial for wheat breeding. In this study, we identified a wheat NAC gene (TaNAC071-A) that is strongly associated with drought tolerance. Overexpression of TaNAC071-A improved drought tolerance in wheat through increased expression of stress-responsive genes and improved water-use efficiency. We also found that a 108-bp insertion in the promoter region of TaNAC071-A contributes to variation in drought tolerance among wheat accessions. Importantly, introgression of this insertion allele into drought-sensitive cultivars improved their drought tolerance, making it a valuable genetic resource for wheat breeding.