Virulence monitoring of the northwestern population of Puccinia triticina in 2023-2025
Abstract
Leaf rust, caused by Puccinia triticina, is a widespread disease of wheat in all regions of Russia, including the North-West. Long-term population-genetic studies of the pathogen make it possible to assess the dynamics of pathogen virulence variability and adjust breeding for resistance strategies. The work aimed to monitor the virulence and race composition of the northwestern population of P. triticina in 2023–2025 and to assess its long–term variability dynamics (2001–2025). High effectiveness of genes Lr9, Lr19, Lr25, Lr28, Lr29, Lr41 (=Lr39), Lr42, Lr47, Lr50, Lr51, Lr53 and Lr57 in the North-West is shown. In 2024–2025, pathogen isolates virulent to carriers of the previously highly effective Lr24 gene were found. In total, 17 phenotypes (races) were identified in the northwestern population in 2023–2025, and only four of them were recorded in 2000–2023. The ong-term variability of the Northwestern population mainly affects the virulence frequency variation of the pathogen to Thatcher lineages by genes Lr2a, Lr2b, Lr2c and Lr15. It decreased significantly in the 2020s. The northwestern population showed its stable consistent variability in 2001–2025. The 2001–2010 populations differed moderately from 2012–2019 and more significantly from 2020–2024. The 2025 pathogen collection was significantly different from those analyzed previously. Additionally, P. triticina collected on wheatgrass in 2025 showed high similarity of virulence to the samples from soft wheat. This confirms that wheatgrass may serve as a reservoir of leaf rust infection for soft wheat crops in the Northwest and contribute to the diversity of the regional pathogen population.