Variation in Virulence, Plasmid Content, and Genes for Coronatine Synthesis Between<i>Pseudomonas syringae</i>pv.<i>morsprunorum</i>and<i>P. s. syringae</i>from<i>Prunus</i>

Abstract

Strains of Pseudomonas syringae pv. morsprunorum and P. s. syringae from Prunus were examined for virulence to cherry, plasmid DNA content, and coronatine synthesis genes. Michigan strains of P. s. syringae spread faster through cherry rootstock plantlets than did strains of P. s. morsprunorum. Twenty-six strains of P. s. morsprunorum, regardless of geographic origin, contained three to seven plasmids of variable size. Twenty-two strains of P. s. syringae contained zero to two plasmids. Among 319 field strains of P. s. morsprunorum from cherry (Prunus cerasus and Prunus avium) orchards in Michigan, 98% contained genomic DNA that hybridized with two DNA probes for coronatine synthesis genes cloned from P. s. tomato