Molecular Identification of Streptomyces scabies causal agent of Potato Common Scab in East Azerbaijan and Kurdestan Provinces

Common scab which caused by Streptomyces scabies and other closely related species is a serious disease of potato and other tuber crops such as beet, radish, and turnip and etc. Although, the potato is one of the most important food crop in Northwest of Iran and common scab disease is prevalent in these areas, there is no accurate information about the exact causal agent of potato common scab and also their strains distribution in the area.
Material and During 2010-2012 harvesting seasons, potato tubers with common scab symptoms were collected from different fields in East Azerbaijan and Kurdistan provinces. Collected isolates were characterized based on morphological and physiological and biochemical assays. Also PCR assay was performed using universal primer for Streptomyces genus and specific primer for S. scabies species. Pathogenicity assay was performed on potato slices and radish seedlings too.
Based on morphological and physiological characteristics and biochemical test, 32 bacterial strains were identified as Streptomyces. Pathogenicity assay were positive in 26 isolates. All selected 32 isolates were amplified a 1027-bp fragment with using universal primer for Streptomyces genus and 26 isolates were amplified a 475-bp fragment using a pair primers which specific for S. scabies and its closely related plant pathogenic species. The PCR assay for detection of taxtomine (txtA) showed that all selected 26 pathogenic isolates could produce expected 522-bp band which indicating a significant correlation between pathogenicity capability of isolates on potato slices and radish seedlings and existing of txtA gene.
Discussion and This is the first report of molecular identification of S. scabies in Northwest of Iran. The results demonstrated that there is significant distribution of this pathogen in the potato farms of Azerbaijan and Kurdistan provinces.