RELATEDNESS OF STRAINS OF XANTHOMONAS-FRAGARIAE BY RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM, DNA-DNA REASSOCIATION, AND FATTY-ACID ANALYSES

The levels of relatedness of strains of Xanthomonas fragariae collecte d over several years from locations in Canada and the United States we re compared by determining fatty acid methyl ester profiles, restricti on fragment length polymorphisms (RFLP) based on pulsed-field gel elec trophoresis (PFGE) analysis, and DNA-DNA reassociation values. Based o n qualitative and quantitative differences in fatty acid profiles, the strains were divided into nine groups and four groups by the MIDI ''1 0% rule'' and unweighted pair analysis, respectively. Restriction anal ysis of genomic DNA by PFGE with two endonucleases (XbaI and SpeI) rev ealed four distinct profiles. When a third endonuclease (VspI) was use d, one group was divided into three subgroups. The profile of the Amer ican Type Culture Collection type strain differed from the profile of every other strain of X. fragariae, Considerable diversity was observe d within X. fragariae, although the majority of the strains represente d a clonal population. The four groups based on fatty acid profiles we re similar to the four groups based on RFLP, but neither method relate d groups to the geographic origins of the strains. The DNA-DNA reassoc iation values were high for representative strains, providing evidence that all of the strains belong to the same species.