ZmMYB104 Enhances Heat-Stress Tolerance by Activating ZmCAT2 Expression in Maize.

Temperature fluctuations critically affect plant growth, but the molecular mechanisms that underlie heat-stress tolerance in maize (Zea mays L.) remain to be fully characterized. Here, we examined the role of the MYB transcription factor ZmMYB104 in thermotolerance regulation and identified its downstream target genes. Through molecular cloning and expression analysis, we demonstrated that ZmMYB104 transcription is induced by heat in maize seedlings. Subcellular localization assays confirmed its presence in the nucleus, and transactivation assays demonstrated its ability to activate transcription. Overexpression lines exhibited greater heat-stress resistance than wild-type. Integration of RNA sequencing and DNA affinity purification sequencing (DAP-seq) revealed that the catalase gene ZmCAT2 was a direct target of ZmMYB104. Electrophoretic mobility shift assays confirmed that ZmMYB104 bound to the ZmCAT2 promoter, and dual-luciferase reporter assays quantified its ability to activate ZmCAT2 transcription. Overexpression ZmMYB104-mediated upregulation of ZmCAT2 significantly increased hydrogen peroxide (HO) scavenging capacity under heat stress, effectively reducing reactive oxygen species accumulation and oxidative damage. These findings demonstrate that ZmMYB104 confers thermotolerance through direct transcriptional activation of the catalase gene ZmCAT2, which encodes a key enzyme in ROS detoxification. Our data provide the first evidence for a ZmMYB104-ZmCAT2 regulatory module that functions in plant heat-stress responses, advancing our understanding of the transcriptional networks that govern thermotolerance in cereal crops. The ZmMYB104-ZmCAT2 axis represents a promising genetic target for the development of climate-resilient maize varieties through molecular breeding strategies.