همراهی Streptomyces caniscabiei و S. bobili با بیماری جرب معمولی سیب زمینی در استان کرمان

Potato common scab disease (PCSD) considerably reduces the quality and marketability of potatoes. Different Streptomyces species were reported as causal agents of the PCSD worldwide. This study aimed to identify Streptomyces species associated with the disease in Kerman province. To achieve this, potato fields in the province were surveyed from 2022 to 2024, and potato tubers showing scab symptoms were sampled. Then, extracts were prepared from the symptomatic tissues and cultured on a water-agar medium on Petri plates. After the inoculated Petri dishes were incubated at 28 °C, DNA was extracted from the grown colonies resembling the Streptomyces genus. Subsequently, the DNA samples were evaluated for the presence of pathogenicity genes using specific primers in polymerase chain reactions (PCRs). Moreover, specific PCRs were performed using reported primers to identify plant pathogenic species belonging to the genus. Then, considering the trpB gene's importance in identifying the genus species, as emphasized in recent studies, the gene was amplified from isolated strains and sequenced. As a result, the pathogenicity genes of txtAB, txtA, and tomA types were detected in all strains; however, the DNA bands were amplified in none using reported-specific primers for plant pathogenic Streptomyces species. Phylogenetic analysis of the trpB gene sequences identified four strains closely related to S. caniscabiei species, while one strain corresponds to S. bobili species. The former was first reported in the USA, Egypt, and China, whereas the latter was from China. Considering that Kerman province is one of the leading provinces of potato production in Iran, and on the other hand, due to the widespread common scab in the region, it is necessary to identify the species associated with the disease and its control management.