AtWRKY1 negatively regulates the response of Arabidopsis thaliana to Pst. DC3000.

WRKY transcription factors (TFs) play a major role in resistance to plant diseases, but the role of AtWRKY1 in response to Pst. DC3000 is not clear. In this study, we found that AtWRKY1 negatively affected the response of Arabidopsis to Pst. DC3000. During Pst. DC3000 infection, the transcription of AtWRKY1 was suppressed. The wrky1 mutants displayed enhanced resistance to Pst. DC3000. In contrast, the overexpression of AtWRKY1 reduced the resistance. The relative RNA levels of defense related PR genes were increased in the loss-of-function mutants, whereas their expressions were decreased in the AtWRKY1-overexpressing plants. Further research revealed that salicylic acid (SA) can repress the expression of AtWRKY1, and overexpression of AtWRKY1 weakened the SA-mediated defense response. In addition, the AtWRKY1 protein can bind to the PR1 promoter in vivo and in yeast cells directly, thereby inhibiting the transcription of PR1. AtWRKY1 indirectly represses the expression of PR2 and PR5. Our results indicated that the AtWRKY1 gene negatively regulates the plant defense responses to Pst. DC3000 through SA signaling pathways.