Genetic characterization of Pseudomonas fluorescens SBW25 rsp gene expression in the phytosphere and in vitro.

ABSTRACT: The plant-colonizing Pseudomonas fluorescens strain SBW25 harbors a gene cluster (rsp) whose products show similarity to type III protein secretion systems found in plant and animal pathogens. Here we report a detailed analysis of the expression and regulation of the P. fluorescens rsp pathway, both in the phytosphere and in vitro. A combination of chromosomally integrated transcriptional reporter fusions, overexpressed regulatory genes, and specific mutants reveal that promoters controlling expression of rsp are actively transcribed in the plant rhizosphere but not (with the exception of the rspC promoter) in the phyllosphere. In synthetic medium, regulatory (rspL and rspR) and structural (rspU, plus the putative effector ropE) genes are poorly expressed; the rspC promoter is subject to a

SUBMITTER: Jackson RW 

PROVIDER: S-EPMC1317024 | biostudies-literature | 2005 Dec

REPOSITORIES: biostudies-literature