Phosphorylation of ZmNAC84 at Ser-113 enhances the drought tolerance by directly modulating ZmSOD2 expression in maize

NAC (NAM, ATAF1/2, and CUC2) transcription factors play vital roles in response to multiple abiotic stresses. Our previous study has demonstrated that ZmNAC84, a maize NAC transcription factor, enhanced the drought tolerance by increasing abscisic acid (ABA)-induced antioxidant enzyme activities of APX and SOD, and Ser-113, a key phosphorylation site, of ZmNAC84 played an important role in this process. However, the target gene of ZmNAC84 in this process is still unknown. Here, we found that ZmNAC84 only regulated the luciferase activity driven by ZmSOD2 promoter in tobacco. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assay showed that ZmNAC84 directly bound to the CACGTG motif of ZmSOD2 promoter. Furthermore, phosphorylation of ZmNAC84 at Ser-113 up-regulated the ZmSOD2 expression by enhancing the DNA binding ability of ZmNAC84 to ZmSOD2 promoter and improved the drought tolerance. Taken together, our results demonstrate that ZmNAC84 directly regulates ZmSOD2 expression to enhance drought tolerance and Ser-113 of ZmNAC84 is crucial in this process.