Opposing regulation of ZmNAC67 and ZmABH3 by ZmGI2 promotes drought adaptation in maize

Drought stress disrupts reproductive synchrony and severely limits maize yield, yet the role of GIGANTEA2 (GI2) in coordinating drought adaptation with reproductive development remains poorly understood. Here, we integrated loss- and gain-of-function genetic approaches with drought stress experiments, reproductive-stage phenotyping, transcriptomic and DNA-binding analyses, and molecular validation assays to elucidate the function of maize GIGANTEA2 ( ZmGI2 ). Loss of ZmGI2 function reduced leaf relative water content (RWC), antioxidant capacity, survival, reproductive synchrony, and yield under drought, whereas ZmGI2 overexpression improved these traits. Integrated transcriptomic and DNA-binding analyses identified ZmNAC67 and ZmABH3 as candidate direct targets of ZmGI2 . Electrophoretic mobility shift (EMSA) and yeast one-hybrid (Y 1 H) confirmed ZmGI2 binding to their regulatory regions, while dual-luciferase (Dual-LUC) assays showed that ZmGI2 activates ZmNAC67 but represses ZmABH3. ZmNAC67 overexpression enhanced drought tolerance, reduced the anthesis-silking interval (ASI), and was accompanied by increased endogenous abscisic acid (ABA) levels and elevated expression of ABA-associated genes. In contrast, ZmABH3 overexpression increased drought sensitivity, enlarged the ASI, and exacerbated yield loss, while phylogenetic analysis and responses to exogenous gibberellin treatment suggested that ZmABH3 may participate in gibberellin-associated responses. Together, these findings support a central regulatory role for ZmGI2 in coordinating drought adaptation and reproductive development through two functionally opposing downstream branches and highlight potential genetic targets for enhancing maize performance under water limitation.