Function analysis of ZmNAC33, a positive regulator in drought stress response in Arabidopsis.

Drought significantly affects plant growth and has devastating effects on crop production, NAC transcription factors respond to abiotic stresses by activating gene expression. In this study, a maize NAC transcription factor, ZmNAC33, was cloned and characterized its function in Arabidopsis. Transient transformation in Arabidopsis leaves mesophyll protoplasts and trans-activation assays in yeast showed that ZmNAC33 was localized in the nucleus and had transactivation activity. qRT-PCR analysis showed that ZmNAC33 in maize was induced by drought, high salinity and abscisic acid (ABA) stress. Promoter analysis identified multiple stress-related cis-acting elements in the promoter region of ZmNAC33. In ZmNAC33 transgenic Arabidopsis, germination rates were higher than in wild type plants under ABA and osmotic stress at the germination stage, and overexpression lines exhibited higher survival rates and higher antioxidant enzyme activities compared with wild type under drought stress. These results indicate that ZmNAC33 actes as a positive regulator in drought tolerance in plants.