Overexpression of the B rassica rapa transcription factor WRKY 12 results in reduced soft rot symptoms caused by P ectobacterium carotovorum in A rabidopsis and C hinese cabbage

Chinese cabbage ( B rassica rapa L . ssp . pekinensis ), an important vegetable crop, can succumb to diseases such as bacterial soft rot, resulting in significant loss of crop productivity and quality. P ectobacterium carotovorum ssp. carotovorum ( P cc ) causes soft rot disease in various plants, including C hinese cabbage. To overcome crop loss caused by bacterial soft rot, a gene from C hinese cabbage was isolated and characterised in this study. We isolated the B r WRKY 12 gene from C hinese cabbage, which is a group II member of the WRKY transcription factor superfamily. The 645‐bp coding sequence of B r WRKY 12 translates to a protein with a molecular mass of approximately 24.4 kD a, and B r WRKY 12 was exclusively localised in the nucleus. Transcripts of B r WRKY 12 were induced by P cc infection in B rassica . Heterologous expression of B r WRKY 12 resulted in reduced susceptibility to P cc but not to P seudomonas syringae pv. tomato in A rabidopsis . Defence‐associated genes, such as A t PDF 1.2 and A t PGIP 2 , were constitutively expressed in transgenic lines overexpressing B r WRKY 12 . The expression of A t WKRY 12 , which is the closest orthologue of B r WRKY 12 , was down‐regulated by P cc in A rabidopsis . However, the A twrky12‐2 mutants did not show any difference in response to P cc , pointing to a difference in function of WRKY 12 in B rassica and A rabidopsis . Furthermore, B r WRKY 12 in Chinese cabbage also exhibited enhanced resistance to bacterial soft rot and increased the expression of defence‐associated genes. In summary, B r WRKY 12 confers enhanced resistance to P cc through transcriptional activation of defence‐related genes.