ZmSCE1a positively regulates drought tolerance by enhancing the stability of ZmGCN5

SUMMARY Drought stress impairs plant growth and poses a serious threat to maize ( Zea mays ) production and yield. Nevertheless, the elucidation of the molecular basis of drought resistance in maize is still uncertain. In this study, we identified ZmSCE1a, a SUMO E2‐conjugating enzyme, as a positive regulator of drought tolerance in maize. Molecular and biochemical assays indicated that E3 SUMO ligase ZmMMS21 acts together with ZmSCE1a to SUMOylate histone acetyltransferase complexes (ZmGCN5‐ZmADA2b). SUMOylation of ZmGCN5 enhances its stability through the 26S proteasome pathway. Furthermore, ZmGCN5 ‐overexpressing plants showed drought tolerance performance. It alleviated accumulation, malondialdehyde content, and ion permeability. What's more, the transcripts of stress‐responsive genes and abscisic acid (ABA)‐dependent genes were also significantly upregulated in ZmGCN5 ‐overexpressing plants under drought stress. Overexpression of ZmGCN5 enhanced drought‐induced ABA production in seedlings. Taken together, our results indicate that ZmSCE1a enhances the stability of ZmGCN5, thereby alleviating drought‐induced oxidative damage and enhancing drought stress response in maize.