Deletions in the Repertoire of Pseudomonas syringae pv. tomato DC3000 Type III Secretion Effector Genes Reveal Functional Overlap among Effectors

PLoS Pathogens

David J. Schneider¹  André C. Velásquez¹  Alan Collmer²  Alistair B. Russell²  Brian H. Kvitko²  Chia-Fong Wei²  Gregory B. Martin²  Duck Hwan Park² 

[1] Boyce Thompson Institute for Plant Research, Ithaca, New York, United States of America;Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America

关键词: Leaves;    Pseudomonas syringae;    Tomatoes;    Bacterial growth;    Polymerase chain reaction;    Plant bacterial pathogens;    Nicotiana;    Plant pathogens;   

DOI  :  10.1371/journal.ppat.1000388

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The γ-proteobacterial plant pathogen Pseudomonas syringae pv. tomato DC3000 uses the type III secretion system to inject ca. 28 Avr/Hop effector proteins into plants, which enables the bacterium to grow from low inoculum levels to produce bacterial speck symptoms in tomato, Arabidopsis thaliana, and (when lacking hopQ1-1) Nicotiana benthamiana. The effectors are collectively essential but individually dispensable for the ability of the bacteria to defeat defenses, grow, and produce symptoms in plants. Eighteen of the effector genes are clustered in six genomic islands/islets. Combinatorial deletions involving these clusters and two of the remaining effector genes revealed a redundancy-based structure in the effector repertoire, such that some deletions diminished growth in N. benthamiana only in combination with other deletions. Much of the ability of DC3000 to grow in N. benthamiana was found to be due to five effectors in two redundant-effector groups (REGs), which appear to separately target two high-level processes in plant defense: perception of external pathogen signals (AvrPto and AvrPtoB) and deployment of antimicrobial factors (AvrE, HopM1, HopR1). Further support for the membership of HopR1 in the same REG as AvrE was gained through bioinformatic analysis, revealing the existence of an AvrE/DspA/E/HopR effector superfamily, which has representatives in virtually all groups of proteobacterial plant pathogens that deploy type III effectors.

【 授权许可】

CC BY