-

A total fifty strains of Elwinia amyiovora (Burr). Winslow et ai, the causal agent of fire blight disease of po me trees, were isolated from apple,
pear, quince, rose and medlar trees from various regions of Iran and subjected to physiological and biochemical characterization, electrophoresis of protein and plasmid DNA, fatty acid analysis and serological and antibiogram tests.
The results showed that all fifty strains shared similar biochemical as well as physiological properties, soluble protein profile in SDS-P AGE and antibiotic
sensitivities. All E. amyiovora strains possessed two plasmid DNA bands differing in molecular weight in agarose gel electrophoresis. Ouchterolony double diffusion test revealed a single and strong homologous precipitin band against three specific anti-sera tested. Thin-layer chromatography of lipids
showed three major and common spots for all strains used. It is concluded that the Iranian strains of E. amylovora originated from different geographical regions are considered homologous and non-distinctive.