Genetic Relatedness Among the DifferentGenetic Lineages of Pseudomonas syringaepv. phaseolicola

摘要

Pseudomonas syringae pv. phaseolicola is an economically importantpathogen of bean (Phaseolus vulgaris L.) and a research model in phytobacteriology.The analysis of the physiological and genetic variability differentiates the strainsisolated from kudzu (Pueraria lobata) and the strains that do not produce phaseolo-toxin from most of the common bean strains. We evaluated several techniques tostudy the variability of P. syringae pv. phaseolicola and the genetic relatednessamong these three groups of strains, in order to understand its epidemiology andthe main mechanisms operating the evolution of its virulence gene complement.Insertion sequence typing with 1S801 revealed substantial variability among 32 P.syringae pv. phaseolicola strains, and allowed the differentiation of three groups ofstrains. This classification agrees with the grouping resulting from ribotyping andwith previous results of other researchers, suggesting that IS801 fingerprinting is avaluable tool to study genetic variability. Our results support the idea that strainsfrom kudzu form a group differentiable from the other types of strains, and thatnontoxigenic strains might represent an ancestor of P. syringae pv. phaseolicolabefore it acquired the phaseolotoxin biosynthesis genes