JWSS - Journal of Water and Soil Science

During summer of 2004, tuber and stem samples of potato plants showing wilt symptoms were sampled from different fields of East Azarbaijan, Fars and Karaj provinces. A total of 39 bacterial strians were isolated and based on the morphological, biochemical characters and pathogenicity tests were divided in to two district group. All the strains of East Azarbijan and Karaj provinces were identifeid as race 3 / biovar 2A of Ralstonia solanacearum and strians of Fars province were identified as race 3 / biovar N2 of the bacterium. Distinct differences were observed in utilization of carbon (D-trehalose, D-ribose and tartrate) as well as tyrosinase activity and protein profiling in SDS-PAGE among the two biovars. Based on the results of phenotypic tests, eight strians of biovar 2A were selected and their plasmids were extracted and electrophoresis on 0.7% agarose gel. All the strians had a single plasmid with similar size and no variation was observed among the strains. According to available literature, this is the first report of occurrence of biovar N2 of R. solanacearum in Iran.