DIFFERENTIATION OF ERWINIA-AMYLOVORA STRAINS BY PULSED-FIELD GEL-ELECTROPHORESIS

Erwinia amylovora strains, isolated from several host plants in variou s geographic regions during different years, were analyzed by pulsed-f ield gel electrophoresis (PFGE) after digestion of the DNA from lysed, agar-embedded cells with rare-cutting restriction enzymes, The bandin g patterns obtained with enzyme XbaI digests revealed significant diff erences among strains from different areas, North American strains E9 and Ea-Rb, a Rubus strain, were highly divergent from other E. amylovo ra strains, French strains were different from central European and En glish strains, E. amylovora strains from central Europe and New Zealan d had identical PFGE patterns, as had strains from Egypt, Greece, and Turkey, PFGE of genomic DNA hom American and English strains gave rise to dissimilar patterns, Patterns of some American strains resembled t hose from strains isolated in other parts of the world, The restrictio n fragment length polymorphisms observed by PFGE analysis can be used to group strains and may give hints about the course of distribution o f the plant disease, From the sizes of the restriction fragments obtai ned, a molecular mass of approximately 4.5 Mb was calculated for the g enome of E. amylovora.