In order to characterize Streptomyces strains that induce potato scab disease, samples were collected from fields in Hamedan, Esfahan, Khorasan and Chahar Mahal-e Bakhtiary provinces during 2000. Forty six pathogenic strains were selected and grouped in three groups through protein electrophoresis. Protein electrophoretic patterns in the first group were similar to those in standard strains of S. scabies Mss94-DD4, S. scabies P-SH-2 and S.scabies Msh2 but different from those in standard strains of S. acidiscabies and S. stelliscabies, in the fifth phenon being similar to those of S. acidiscabies. These strains possessed 12-18 fatty acids with two dominant fatty acids that had similar R¬f with standard strains according to GC and TLC analysis. Due to considerable varietion among strains and phena, there would be new species or subspecies probable among these strains.
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