Overexpression of a maize WRKY58 gene enhances drought and salt tolerance in transgenic rice

WRKY transcription factors (TFs) are reported to play crucial roles in the processes of plant growth and development, defense regulation and stress responses. In this study, a WRKY group IId TF, designated ZmWRKY58, was isolated from maize (Zea mays L.). Expression pattern analysis revealed that ZmWRKY58 was induced by drought, salt and abscisic acid treatments. Subcellular localization experiments in onion epidermal cells showed the presence of ZmWRKY58 in the nucleus. Overexpression of ZmWRKY58 in rice resulted in delayed germination and inhibited post-germination development. Further investigation showed that ZmWRKY58 overexpressing transgenic plants had higher survival rates and relative water contents, but lower malonaldehyde contents and relative electrical leakage compared with wild-type plants, following drought and salt stress treatments, suggesting that overexpression of ZmWRKY58 leads to enhanced tolerance to drought and salt stresses in transgenic rice. Additionally, yeast two-hybrid assay showed that ZmWRKY58 could interact with ZmCaM2, suggesting that ZmWRKY58 may function as a calmodulin binding protein. Taken together, these results suggest that ZmWRKY58 may act as a positive regulator involved in the drought and salt stress responses.