Poster Session: Molecular and Cellular Plant-Microbe Interactions - Proteomics/Metabolomics/Genomics
758-P
Genome analysis of nonpathogenic Pseudomonas syringae: secretion systems, effectors and toxins.
G. BUSOT (1), M. Arif (1), J. P. Stack (1)
(1) Department of Plant Pathology, Kansas State University, Manhattan, KS, U.S.A.
Pseudomonas syringae populations are global in distribution occupying a very wide array of habitats and comprised of pathogenic and nonpathogenic strains. To better understand the basic differences among pathogenic and non-pathogenic strains of P. syringae, comparative genomic analyses were performed targeting two major systems required for survival and reproduction: secretion and virulence. The complete genome of P syringae pv. syringae (Psy B728a) was used to compare draft genomes of four nonpathogenic strains of P. syringae (ESC-10, ESC-11, Ps Cit7 and BRIP39023). Psy B728a, Cit7 and BRIP39023 genomic sequences were downloaded from the NCBI GenBank. Draft genomes of ESC-10 and ESC-11 were obtained after sequencing and de novo assembly of paired-end libraries (Illumina MiSeq). Genomic comparisons revealed large differences between pathogenic and nonpathogenic strains and among nonpathogenic types. All targeted gene clusters were found in the pathogenic strain used as a reference. The hrp-hrc cluster encoding structural and regulatory components of the type III secretion system was only absent in Ps ESC-11. Nonpathogenic strains had a relatively small number of effector genes compared to pathogenic strains and some of them appeared truncated. The gene cluster encoding for syringolin A, a peptide derivative that activates non-host plant defense related genes, was absent in ESC-11. Several genes within the syringopeptin gene cluster appeared to be truncated. In contrast, syringomycin gene cluster was present in all four nonpathogenic strains analyzed. Genome analyses suggest that pathogenic and nonpathogenic strains of P. syringae might best be considered a continuum rather than as discrete taxonomic entities.