Pseudomonas syringae Catalases Are Collectively Required for Plant Pathogenesis

Authors

Ming Guo, University of Nebraska-LincolnFollow
Anna Block, University of Nebraska-LincolnFollow
Crystal D. Bryan, Tufts University
Donald F. Becker, University of Nebraska-LincolnFollow
James R. Alfano, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2012

Citation

Journal of Bacteriology (2012) 194(18) p. 5054-5064. doi:10.1128/JB.00999-12

Comments

Copyright © 2012, American Society for Microbiology. Used by permission.

Abstract

The bacterial pathogen Pseudomonas syringae pv. tomato DC3000 must detoxify plant-produced hydrogen peroxide (H₂O₂) in order to survive in its host plant. Candidate enzymes for this detoxification include the monofunctional catalases KatB and KatE and the bifunctional catalase-peroxidase KatG of DC3000. This study shows that KatG is the major housekeeping catalase of DC3000 and provides protection against menadione-generated endogenous H₂O₂. In contrast, KatB rapidly and substantially accumulates in response to exogenous H₂O₂. Furthermore, KatB and KatG have nonredundant roles in detoxifying exogenous H₂O₂ and are required for full virulence of DC3000 in Arabidopsis thaliana. Therefore, the nonredundant ability of KatB and KatG to detoxify plant-produced H₂O₂ is essential for the bacteria to survive in plants. Indeed, a DC3000 catalase triple mutant is severely compromised in its ability to grow in planta, and its growth can be partially rescued by the expression of katB, katE, or katG. Interestingly, our data demonstrate that although KatB and KatG are the major catalases involved in the virulence of DC3000, KatE can also provide some protection in planta. Thus, our results indicate that these catalases are virulence factors for DC3000 and are collectively required for pathogenesis.