Phenotypic and Molecular Characterization of Streptomyces enissocaesilis and Streptomyces caviscabies Induced Potato Common Scab in Egypt.
2025
Eihab Mohamed Taha | Omnia Ahmed Abd El-Hafez
Potato common scab incited by pathogenic Streptomyces spp. is a significant soil-borne disease leading to serious economic losses in potato tubers worldwide. However, there is limited information available in Egypt regarding the pathogenicity, prevalence, and variety of Streptomyces spp. inciting common scab. Therefore, this study aims to clarify the aspects of identifying and characterizing Streptomyces spp. obtained from scabby tubers as well as to evaluate their pathogenicity. In the present investigation, nine isolates of Streptomyces spp. were obtained from various scab lesion symptoms. Of these, the Ag2 and Man strains exhibited pathogenic traits. The pathogenicity assays demonstrated that the strains induced necrotic lesions on tuber slices and abnormal growth of radish seedlings. In potato pot trail, The Ag2 isolates caused deep-pitted lesions with a disease index of 73.30%. Additionally, tubers inoculated with the Man isolate exhibited visible brown raised lesions, resulting in a disease index of 63.97%. Subsequently, the strains were characterized based on morphological, physiological, biochemical and phylogenetic levels. Phylogenetic tree derived from 16S rRNA gene sequences revealed that Ag2 and Man strains share 100% sequence similarity with Streptomyces caviscabies ATCC 51928 and Streptomyces enissocaesilis NRRL B-16365, respectively. The results of this study demonstrate that S. caviscabies and S. enissocaesilis are capable of causing CS disease in potatoes and may pose a potential threat to potato cultivation in Egypt.
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