VIRULENCE OF PSEUDOMONAS SYRINGAE STRAINS FROM SORIZ (SORGHUM ORYSOIDUM) AND THEIR SPECIALIZATION

Abstract

Objective. To study the virulence properties of Pseudomonas syringae strains isolated from soriz and various representatives of sorghum crops in Ukraine and to establish the sensitivity range of plants to these pathogens. Methods. Ten strains freshly isolated from soriz (Sorghum orysoidum) were used to study virulence properties, namely: Pseudomonas syringae 210342, 211141a, 211141, 210341, 21034, 210541b, 210541, and Pseudomonas sp. 210521, 21052, 21054, pathogenic strains of sorghum crops from the collection of the Department of Phytopathogenic Bacteria of D. K. Zabolotny Institute of Microbiology and Virology of the National Academy of Sciences of Ukraine and collection strains of phytopathogens that can be potential causative agents of bacterial diseases of soriz or are causative agents of diseases of agricultural crops that can be used in crop rotation. The virulence properties of strains isolated from sorghum were determined on plants of the genus Sorghum. To establish the range of crops sensitive to these pathogens, a number of plants belonging to other genera and families, both cultivated and weed, were tested. Artificial inoculation was carried out in the greenhouse and in the field as injection of bacterial suspension of 1×109 CFU/mL into the leaf surface and stem at all phases of the development of soriz and sorghum cultures. Accounting for artificial contamination was carried out in 7 to 14 days using a locally modified 6-point scale. Aggressiveness of bacteria was assessed by the size of necrosis that formed at the site of injection of the bacterial suspension. Aggressiveness was calculated as the arithmetic mean of the results. Results. P. syringae strains isolated from soriz were found to be virulent for soriz and sorghum crops, however, heterogeneous in aggressiveness. The most aggressive strains were P. syringae 211141a, 210341, and 21034. Some collection strains, isolated from different cultures, showed higher aggressiveness against sugar and grain sorghum than against soriz and Sudan grass. The studied strains of phytopathogens were found to affect segetal vegetation; the most sensitive to the studied strains were horsetail, field bindweed, goldenrod. They showed high aggressiveness against setaria, ragweed, and common sedge. Strains of P. syringae affecting potato, beet, sunflower and tomato plants were identified. Conclusion. Pseudomonas syringae strains isolated from contaminated sorghum plants are virulent and capable of infecting a wide range of plants, including plants of the sorghum family, other types of agricultural crops, and various types of segetal vegetation. Strains of Pectobacterium carotovorum, Xanthomonas vasicola pv. holcicola, Diskeya chryzanthemy, Pantoea agglomerans can be potential pathogens of sorghum crops. The results indicate that segetal vegetation can serve as a reservoir of bacterial infections and play a role in the transfer of bacterial pathogens.