Characterization of Erwinia amylovora strains using random amplified polymorphic DNA fragments (RAPDs).
Genetic diversity of 16 strains of E. amylovora, representing different host plant origins and geographical regions, was investigated by RAPD analysis. A strain of E. herbicola and another of Agrobacterium vitis were used as outgroups. Different RAPD fragments were produced by polymerase chain reaction amplification with 6 different 10-mer primers. RAPD banding profiles were found that enabled the E. amylovora strains to be distinguished from one another. Cluster analysis based on the number of RAPD fragments shared between strains showed that strains of E. amylovora isolated from subfamily Pomoideae formed a single group, whereas 2 strains from Rubus (subfamily Rosoideae) formed a second group. Two strains isolated from Asian pear on Hokkaido, Japan, formed a third group. Sets of RAPD fragments were identified that enabled each of the 2 host-range groups and 1 geographical region (Hokkaido) of E. amylovora strains to be unambiguously distinguished from 1 another and from the outgroups. This study showed that strains of E. amylovora exhibited genetic diversity detectable by RAPD analysis and that molecular and statistical analysis of RAPD fragments can be used both to distinguish between strains and to determine relatedness between them.