Dissecting the regulon of the two-component system CvsSR: Identifying new virulence genes in Pseudomonas syringae pv. tomato DC3000    
M. FISHMAN (1), P. Stodghill (2), M. Filiatrault (2) (1) Cornell University, U.S.A.; (2) USDA-ARS, U.S.A.

Recognition of environmental changes and regulation of genes that allow for adaption to those changes is essential for bacterial survival. Two-component systems (TCSs) allow bacteria to sense and adapt to their environment. We previously identified the TCS CvsSR in the bacterial plant pathogen Pseudomonas syringae pv. tomato DC3000 (Pto), and showed that ?cvsS and ?cvsR strains displayed reduced growth and symptom development in tomato and Arabidopsis. CvsSR is induced by cations, such as Ca(II), and regulates aggregation and motility in Pto. In order to identify the regulon of CvsSR we used RNA-seq and ChIP-seq. The transcriptional profile of ?cvsR strains compared to wild-type (WT) shows increased expression of genes related to oxidative stress when grown under Ca(II) concentrations comparable to those found in the tomato apoplast. Similarly, the gene for catalase, katB, is found within the primary regulon of CvsSR. This suggests that CvsSR regulates the oxidative stress response in Pto. A putative carbonic anhydrase encoded by cynT is one of the most highly regulated genes in primary regulon of CvsSR. To investigate if CynT plays a role in virulence, we constructed a ?cynT strain and tested for virulence on tomato. We found that the ?cynT strain shows reduced growth and symptom development compared to WT. Carbonic anydrases have antioxidant properties and therefore we speculate that CynT acts as an antioxidant in Pto.

Abstract Number: P6-141
Session Type: Poster