Virulence of Pseudomonas syringae pv. tomato DC3000 is modulated through the Catabolite Repression Control protein Crc
S. CHAKRAVARTHY (1), B. Butcher (1), K. D’Amico (2), Y. Liu (1), M. Filiatrault (2) (1) Cornell University, U.S.A.; (2) USDA/ARS, and Cornell University, U.S.A.

Pseudomonas syringae (P.s.) infects diverse plant species and several P.s. pathovars have been used in the study of molecular events that occur during plant-microbe interactions. Although the relationship between bacterial metabolism, nutrient acquisition and virulence has attracted increasing attention in bacterial pathology, it is largely unexplored in P.s. The Crc (catabolite repression control) protein is a putative RNA-binding protein that regulates carbon metabolism and a number of virulence factors in the Pseudomonads. We deleted crc in P.s. pv. tomato DC3000 and found that Crc plays a role in virulence related processes. The mutant showed reduced swarming ability while demonstrating enhanced biofilm formation. Furthermore, the mutant showed reduced growth and symptoms in hosts tomato and Arabidopsis compared to wild type (WT) DC3000. DC3000Δcrc showed reduced Hypersensitive Response (HR) in non-hosts Nicotiana benthamiana and tobacco. It was more susceptible to hydrogen peroxide in culture than WT. In N. benthamiana tissues induced for PAMP-triggered immunity, Δcrc caused even further delayed HR compared to WT. However, both WT and Δcrc elicited similar reactive oxygen species (ROS) responses in N. benthamiana. We conclude that Crc plays an important role in the virulence of DC3000, and speculate that it may control the expression of genes that protect DC3000 from oxidative stress as well as others factors required for adaption and survival in the plant environment.

Abstract Number: P7-160
Session Type: Poster