ZmHDZ6 positively regulates drought tolerance in maize seedlings by activating ZmPRX6 and ZmEPF2

Maize is a cornerstone of global agriculture, serving as a staple crop for millions worldwide. While drought in seedling stage is a formidable challenge for its survival and subsequently development, significantly impacting agricultural productivity and food security worldwide. The identification and understanding of key genes involved in drought resistance at seedling stage are crucial for developing elite maize varieties. In this study, we characterized ZmHDZ6, a candidate gene, coding a transcription factor, mainly involved in drought-resistance at the seedling stage. Overexpression of ZmHDZ6 in maize significantly enhanced drought tolerance and improved water-use efficiency, primarily by reducing leaf stomatal density of transgenic lines under drought stress. Further study uncovered that ZmHDZ6 directly binds to the promoters of ZmPRX6 and ZmEPF2 and activates their expression, with CAAT-AT identified as the core recognition motif. Moreover, we identified a favorable allele of ZmHDZ6, offering a valuable genetic resource and selection target for exploiting natural variation in maize drought tolerance.