Natural variation in ZmDapF1 enhances maize drought resilience

As drought severely threatens the stability of crop yields, it is crucial to develop cultivars with enhanced drought resilience. Here we demonstrate that natural variation in ZmDapF1, encoding a putative diaminopimelate epimerase, contributes to maize drought-stress resistance without compromising grain yield. ZmDapF1 inhibits the activity of ZmMDH6, a chloroplast NADP-dependent malate dehydrogenase. ZmDapF1 gene knockout mutants exhibited significantly enhanced seedling viability and grain yield under drought stress, while maintaining high yields under normal field conditions. Natural variations in the ZmDapF1 promoter increase its binding affinity to a MYB transcription factor, ZmMYB121, which represses ZmDapF1 expression under drought. Therefore, ZmMYB121 plays a positive role in drought resistance. Knocking out ZmDapF1 resulted in increased ZmMDH6 activity, enhanced photosynthetic rate and reduced reactive oxygen species accumulation under drought, which may confer the enhanced drought resilience. Thus, genetic engineering targeting ZmDapF1 holds great potential for developing maize varieties with improved drought resilience.