Virulence Variability of Puccinia triticina in the Western Region of the High-Latitude Asian Spring Wheat Belt

A comprehensive virulence survey of Puccinia triticina collections was conducted in 2025 across four regions of Asian Russia and northern Kazakhstan to analyze the extent of differentiation among the regional pathogen populations. Leaves with uredinia were collected on a standardized set of spring wheat genotypes from the Kazakhstan–Siberia Network (KASIB-26). A total of 195 single-pustule isolates (34 from Chelyabinsk, 24 from Kurgan, 52 from Tyumen, 43 from Omsk, and 42 from northern Kazakhstan) were tested for the infection type on the standard set of twenty Thatcher near-isogenic wheat lines. None of the 20 Lr-genes represented in the differential lines proved to be highly effective. New virulences to Lr24 and to the gene combination Lr9 + Lr26 were first revealed in the studied area. In total, 22 races were identified. Two races were identified across all five regions, one in three regions, and four in two regions. Alongside traditional races in the northwesternmost wheat-growing territories in Asia, new races with previously absent virulences were detected in 2025. Distinct pathogen groups were identified within the Omsk and Tyumen regions, and a highly unique race was found in Kazakhstan. Nevertheless, the overall population structure remained stable during the last decade, with a predominant combination of highly virulent races persisting across the whole territory.