Structural Variability of the Wheat Leaf Rust Pathogen <i>Puccinia triticina</i> in Russia in 2019–2024

ABSTRACT The structural analysis of the Russian Puccinia triticina population based on a virulence survey during 2019–2024 is presented. The studied areas included the European (North West, Volga, North Caucasus and Dagestan) and Asian (Ural, West Siberia) regions. Single pustule isolates were tested for virulence on a standard set of 20 Thatcher differential lines. A total of 53 virulence phenotypes of P. triticina were detected among 689 isolates tested. Substantial virulence variability between regions was revealed in the lines with Lr2a , Lr2b , Lr2c and Lr15 genes; this was much lower in Dagestan, North Caucasus and North West. Virulence to Lr9 occurred annually in the Asian regions but was not observed or was rare in the European regions. Three races, MCTKH, MCTKG and THTTR, were observed in all regions. T‐races were more frequent in the Ural, West Siberian and Volga regions, whilst P‐ and M‐races were more frequent in North West, North Caucasus and Dagestan. The P. triticina populations were divided into two distinct regional groups, Western and Eastern. The first group included North West and North Caucasus, while the Dagestan pathogen collection was closer to them than to other regions. The second group included the Ural and West Siberia collections, and to a lesser extent the Volga region. Comparison of phenotypes in the Western and Eastern populations and statistics of wind data in summer would suggest that the prevailing direction of pathogen migration is west‐to‐east. The structural variability of the Russian population of P. triticina has remained similar since the 1980s.