Phenotypic diversity in Pseudomonas syringae pv. tomato

Abstract

Twenty-nine strains of Pseudomonas syringae pv. tomato (P. s. tomato) that represented the temporal and geographical diversity of this pathogen were tested for pathogenicity on tomato, carbohydrate utilization, bacteriophage sensitivity, fatty acid composition and plasmid profile. The extent of phenotypic diversity observed with P. s. tomato depended on the trait examined; the strains were similar in pathogenicity, carbohydrate utilization and fatty acid content, whereas greater diversity was found in bacteriophage sensitivity and the plasmid profiles. A classification scheme for P. s. tomato plasmids based on both size and DNA homology is proposed. The array of phenotypic traits clearly differentiated all the strains of P. s. tomato examined from six strains of P. syringae pv. syringae, with carbohydrate utilization and fatty acid analyses being the most reliable.