CHARACTERIZATION OF ERWINIA-AMYLOVORA STRAINS USING RANDOM AMPLIFIED POLYMORPHIC DNA FRAGMENTS (RAPDS)

The genetic diversity among 16 strains of Erwinia amylovora, chosen to represent different host plant origins and geographical regions, was investigated by RAPD analysis, One strain of Erwinia herbicola and one of, Agrobacterium vitis were used as outgroups. Ninety-eight differen t RAPD fragments were produced by polymerase chain reaction amplificat ion with sis different 10-mer primers. RAPD banding profiles were foun d that enabled the Erw. amylovora strains to be distinguished from one another. Cluster analysis based on the number of RAPD fragments share d between strains showed that strains of Erw. amylovora isolated from subfamily Pomoideae formed a single group, whereas two strains from Ru bus (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 two host-range gro ups and one geographical region (Hokkaido) of Erw. amylovora strains t o be unambiguously distinguished from one another and from the outgrou ps. This study shows that strains of Erw. amylovora exhibit genetic di versity detectable by RAPD analysis, and that molecular and statistica l analysis of RAPD fragments can be used both to distinguish between s trains and to determine relatedness between them.