BcWRKY33A Enhances Resistance to via Activating in Non-Heading Chinese Cabbage.

The transcription factor WRKY33 is a vital regulator of the biological process of the necrotrophic fungus (). However, its specific regulatory mechanism remains to be further investigated. In non-heading Chinese cabbage (NHCC, (syn. ) ssp. ), our previous study showed that BcWRKY33A is induced not only by salt stress, but also by infection. Here, we noticed that BcWRKY33A is expressed in trichomes and confer plant defense resistance. Disease symptoms and qRT-PCR analyses revealed that -overexpressing and -silencing lines were less and more severely impaired, respectively, than wild type upon treatment. Meanwhile, the transcripts' abundance of indolic glucosinolates' (IGSs) biosynthetic genes is consistent with plants' tolerance. Identification and expression pattern analysis of BcMYB51s showed that BcMYB51-3 has a similar trend to BcWRKY33A upon infection. Moreover, BcWRKY33A directly binds to the promoter, which was jointly confirmed by Y1H, dual-LUC, and EMSA assays. The importance of MYB51, the homolog of BcMYB51-3, in the BcWRKY33A-mediated resistance was also verified using the TRV-based VIGS system. Overall, our data concludes that BcWRKY33A directly activates the expression of and downstream IGSs' biosynthetic genes, thereby improving the tolerance of NHCC plants.