Grace Petzold

Streptomyces is a genus of gram-positive bacteria that lives and thrives in the soil. The majority of Streptomyces spp. have been found to be helpful to humans and plants alike, producing antibiotics and anticancer drugs for human use and acting as a biocontrol agent against harmful plant pathogens. However, a few Streptomyces spp., including Streptomyces scabies, can cause common scab of potato disease. This disease causes raised textured and deep pitted lesions on the tubers, severely affecting the tuber's quality and marketability. In the current study, we aim to identify Streptomyces spp. causing common scab of potatoes and study their varying pathogenic abilities on different potato cultivars. Using aseptic microbiological techniques, 12 Streptomyces isolates were isolated from three varieties of scab-infected potatoes with varied common scab phenotypes. The preliminary morphological study suggests that they are Streptomyces spp. We are currently isolating the DNA from these isolates and are performing 16SrRNA PCR and sequencing to characterize their identity. In another experiment, we are performing a common scab pot assay to characterize four Streptomyces isolates (two highly pathogenic and two hypo-pathogenic) for their potato cultivar-specific disease phenotype. Overall, we have successfully isolated Streptomyces isolates from potato tubers, and ongoing work will lead to the characterization of their host-specific pathogenicity.