Characterization of an in planta induced peroxidase gene of Ralstonia solanacearum

• Published in: Phytopathology Vol. 96; no. 6; p. S36
• Main Authors: Flores-Cruz, Z, Allen, C
• Format: Journal Article
• Language: English
• Published: 01.06.2006
• Subjects: Lycopersicon esculentum; Ralstonia solanacearum
• ISSN: 0031-949X

In response to pathogen attack, plants produce an oxidative burst composed of active oxygen species (AOS) that have direct antimicrobial effects. Little is known of the pathogen's response to plant derived AOS and the role of oxidative stress response in plant pathogens during disease development. A previous IVET screen found that the bacterial wilt pathogen Ralstonia solanacearum expresses genes involved in the oxidative stress response in planta during mid-phase tomato pathogenesis. Further, bioinformatic analyses reveal that this pathogen carries diverse and redundant genes likely involved in the detoxification of AOS. We hypothesize that genes involved in the oxidative stress response of R. solanacearum are up-regulated in planta, and contribute to both in planta adaptation and survival and to wilt disease development. One such gene is bcp, predicted to encode a peroxidase of the AhpC/TSA family of antioxidants. This gene is up-regulated 20-fold during growth in tomato plants. An R. solanacearum bcp mutant is hypersensitive to hydrogen peroxide and the superoxide-generating agent Paraquat, but grows as well as a wild-type strain in minimal media and in tobacco leaves. These results indicate that bcp encodes a peroxidase required for R. solanacearum's oxidative stress response.