Abstract:

In order to clarify the types of pathogens causing potato common scab in the micro potato continuous cultivation substrate, organic acids with good inhibitory activity were screened to control this disease. In this study, pathogenic bacteria were isolated and purified from diseased potato, and their pathogenicity was detected by potato chip method, radish chip method and greenhouse pot inoculation method. The species were determined by morphological observation, physiological and biochemical characteristics determination and 16S rRNA gene sequence analysis. The biological characteristics such as salt tolerance were studied, the effects of organic acids such as formic acid on the growth of Streptomyces spp. were determined using paper plate method. Streptomyces strain 19311 was pathogenic, and its pathogenic island virulence related genotype was txtAB⁺/tomA⁺/necI⁺. Strain 19311 was identified as Streptomyces acidiscabies based on the morphological, physiological and biochemical characteristics and 16S rRNA sequence analysis. Formic acid, acetic acid, propionic acid, lactic acid, citric acid, and tartaric acid could significantly inhibit the growth of S. acidiscabies, and formic acid had the best antibacterial effect with the antibacterial zone diameter of 45.43 mm and the lowest effective concentration of 1%, which could inhibit the growth of S. acidiscabies by increasing the permeability of cell membrane. In this study, the species and biological characteristics of Streptomyces strain 19311 in the micro potato cultivation substrate were identified. The use of 1% formic acid to control the occurrence of this disease and evaluate its impact on the original seed production can be carried out in the future.

Key words: potato common scab, micro potato, identification, biological characteristics, organic acid, cell membrane permeability, formic acid, inhibitory activity, continuous cropping substrate