Variability of yellow rust pathogen according to virulence on winter common wheat varieties in Krasnodar territory

Yellow rust (pathogen Puccinia striiformis West.) is an economically significant wheat disease in the North Caucasus, the harmfulness of which has been increasing in the last decade. Information on the efficiency of resistance genes and the racial composition of the pathogen is necessary for successful genetic protection of wheat. The purpose of the current study was to characterize the virulence and racial composition of P. striiformis on genetically diverse varieties of winter common wheat grown in the Krasnodar Territory. The study objects were leaves with urediniopustules of P. striiformis collected in 2021–2024 from 16 winter common wheat varieties developed by the National Center of grain named after P.P. Lukyanenko in the Krasnodar Territory. There has been obtained a total of 53 single pustule isolates. Virulence was assessed using 29 virulence testers, namely 14 isogenic lines of the variety ‘Avocet’ (AvNIL) and 15 differentiator varieties. The genes Yr5, Yr10, Yr15, Yr24 and Yr26 were characterized by high efficiency in the region, and they are recommended for breeding for yellow rust resistance. There were identified 16 phenotypes (races) in the studied collection of P. striiformis isolates when tested a full set of 29 differentiators and 10 races on 15 international differentiator varieties. For most varieties, there has been established an attack by an original phenotype, which determines the increased diversity of the Krasnodar population of P. striiformis . At the same time, the analysis of genetic distances between virulence phenotypes has not revealed significant differences between them, which suggests the existence of a single clonal population of the pathogen in this territory. The high evolutionary potential of P. striiformis requires annual monitoring of the virulence and racial composition of the pathogen population, and the search for new effective resistance donors for use in breeding for yellow rust resistance.