APS Abstracts of Presentations

A 16-kb genomic island is differentially represented in Pseudomonas syringae strains with distinct host ranges
Presenter: A. Records, Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX, USA
Co-Author(s): N. Wang, Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX, USA; D. Gross, Department of Plant Pathology & Microbiology, Texas A&M University, College Station, TX, USA
Phytopathology 95:S87

Pseudomonas syringae infects a wide range of ornamental and crop plants, but the interactions between individual P. syringae strains and their respective hosts are very specific. P. syringae host specificity is associated with horizontally-acquired virulence factors, including genes that encode toxins and other secreted proteins. We have identified a 16.2-kb gene cluster that is present in the genomes of P. s. pv. syringae B728a and P. s. pv. tomato DC3000 but is conspicuously absent from other P. syringae strains. This genomic island is positioned within a conserved region of the P. s. s. B728a and P. s. t. DC3000 genomes and is flanked by mobile genetic elements. In addition, the island is present in the genomes of several other bacterial species, including Pectobacterium carotovorum and the human pathogens Salmonella enterica and Yersinia pestis. Many of the genes in the island are predicted to encode virulence factors, including the type III effector HopL and the serine/threonine protein kinase PpkA. Using hopL and ppkA as probes, we have surveyed the genomes of several P. syringae strains to learn about the distribution of this genomic island and address its relationship to host range.

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