Arabidopsis WRKY46 WRKY54 and WRKY70 Transcription Factors Are Involved in Brassinosteroid-Regulated Plant Growth and Drought Responses

摘要

Plant steroid hormones, brassinosteroids (BRs), play important roles in growth and development. signaling controls the activities of BRASSINOSTERIOD INSENSITIVE1-EMS-SUPPRESSOR1/BRASSINAZOLE-RESISTANT1 (BES1/BZR1) family transcription factors. Besides the role in promoting growth, BRs are also implicated in plant responses to drought stress. However, the molecular mechanisms by which BRs regulate drought response have just begun to be revealed. The functions of WRKY transcription factors in -regulated plant growth have not been established, although their roles in stress responses are well documented. Here, we found that three Arabidopsis thaliana group III WRKY transcription factors, WRKY46, WRKY54, and WRKY70, are involved in both -regulated plant growth and drought response as the wrky46 wrky54 wrky70 triple mutant has defects in -regulated growth and is more tolerant to drought stress. RNA-sequencing analysis revealed global roles of WRKY46, WRKY54, and WRKY70 in promoting -mediated gene expression and inhibiting drought responsive genes. WRKY54 directly interacts with BES1 to cooperatively regulate the expression of target genes. In addition, WRKY54 is phosphorylated and destabilized by GSK3-like kinase BR-INSENSITIVE2, a negative regulator in the BR pathway. Our results therefore establish WRKY46/54/70 as important signaling components that are positively involved in -regulated growth and negatively involved in drought responses.