ZmbZIP38 interacts with ZmDnaJ to regulate maize seedling drought tolerance through modulating ABA signaling, stomatal closure and root growth under stress.

Abstract

Key message: The drought stress-responsive transcription factor ZmbZIP38 interacts with ZmDnaJ to regulate maize drought tolerance through modulating ABA biosynthesis and signaling, stomatal closure and root growth under stress. Basic leucine zipper (bZIP) transcription factors (TFs) crucially regulate plant drought stress response. However, how bZIP TFs regulate maize drought tolerance remains elusive. Previously, we demonstrated that ZmDnaJ enhances maize drought tolerance by promoting ABA biosynthesis and stomatal closure. In this study, we have fished out ZmbZIP38 (by yeast one-hybrid analysis) as key interacting partner of ZmDnaJ, and elucidate its function in ZmDnaJ-mediated drought tolerance in maize. ZmDnaJ promoter analysis results showed that ZmbZIP38 directly targets ZmDnaJ by binding to ABRE motifs in the corresponding gene promoters. Overexpression of ZmbZIP38 significantly enhanced maize survival rate under drought stress, which was accompanied by expanded leaf area and higher stomatal closure. ZmbZIP38-overexpressing maize lines also showed enhanced ROS scavenging, reduced H₂O₂ and MDA accumulation, and up-regulated expression of antioxidant enzymes-associated genes. Moreover, ZmbZIP38-OE maize lines exhibited elevated ABA levels under drought stress, correlating with the up-regulated expression of ABA biosynthetic genes. Conversely, zmbzip38 knockdown mutants displayed reduced drought tolerance, evidenced by increased cell damage and decreased leaf area. Collectively, our findings demonstrate that ZmbZIP38 regulates maize seedling drought tolerance by modulating ABA biosynthesis and signaling, ROS scavenging and root growth, highlighting its potential role in abiotic stress response, and particularly enhancing maize drought tolerance.