The Negative Regulators of the Basal Defence WRKY7, WRKY11 and WRKY17 Modulate the Jasmonic Acid Pathway and an Alternative Splicing Regulatory Network in Response to Pseudomonas syringae in Arabidopsis thaliana.

In Arabidopsis thaliana, the transcription factors WRKY7, WRKY11 and WRKY17 act as negative defence regulators against Pseudomonas syringae pv. tomato (Pst) DC3000. However, their coordinated regulation of gene expression has yet to be fully explored. In this study, we conducted a transcriptomic analysis on the triple mutant wrky7/11/17 in response to Pst DC3000 at 0, 3 and 24 h post-inoculation (hpi). Our results suggest that at early infection stages (0 and 3 hpi), WRKY7, WRKY11 and WRKY17 significantly repress a group of genes involved in signal perception and transduction, including receptor-like kinases. Furthermore, at later stages of interaction (24 hpi), these transcription factors induce genes related to the biosynthesis and signalling of the jasmonic acid (JA) pathway. Further infection experiments with Pst DC3000 in plants treated with methyl jasmonate (a JA analogue) and infections with Botrytis cinerea, a pathogen against which JA-mediated responses are crucial for effective defence, support this proposal. Moreover, we analysed the role of WRKY7, WRKY11 and WRKY17 in alternative splicing regulation. A comparison between differentially expressed (DEG) and spliced (DAS) genes revealed that over 80% of DAS events do not occur in conjunction with overall changes in gene expression. Alternative splicing events were found in genes with functions in splicing and the JA pathway, such as ALY4, PRP40A, JAZ3 and JAZ10. These results suggest that WRKY7, WRKY11 and WRKY17 can also participate in this layer of gene expression regulation to modulate immunity negatively.