POPULATION GENETICS STUDY OF THE WHEAT LEAF RUST AGENT <i> PUCCINIA TRITICINA </i> IN DAGESTAN
Leaf rust (causative agent  Puccinia triticina  Erikss.) is a harmful disease of wheat, Aegilops and triticale in Dagestan. Germplasm collections of bread wheat and other  Triticum  and  Aegilops  species are studied every year in the experimental field at the Dagestan Experimental Station of VIR (DES VIR), and evaluated for leaf rust resistance. Monitoring of the pathogen's virulence makes it possible to assess the dynamics of the fungus's variability and correct the results of phytopathological scores performed in different years. The study of the Derbent population has a long history, and has been conducted since 1970. The aim of this work is to analyze the virulence of the  P. triticina  population in 2008-2017. Infectious material was represented by leaves of bread wheat with uredopustules collected in the experimental field of DES VIR in 2008, 2009, 2011, 2014, 2016, and 2017. Populations were cloned to obtain monopustule isolates. For this and for virulence analysis, the laboratory technique of detached leaves preserved in the benzimidazole solution was used. In total, 144 isolates were employed in virulence studies: 32 in 2008, 37 in 2009, 14 in 2011, 14 in 2014, 26 in 2016, and 21 in 2017. The genes Lr9, Lr19, Lr24, Lr28, Lr29, Lr41, Lr42, Lr45, Lr47, Lr50, Lr51, Lr53, and Lr65 were characterized by high efficiency. This means that wheat samples protected by these genes will demonstrate high-level resistance in the fields of southern Dagestan. Variations in virulence frequencies were recorded in Thatcher lines (Tc) with the genes Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr3bg, Lr15, Lr16, Lr20 and Lr26. Using 20 almost isogenic Thatcher lines (TcLr), 20 phenotypes (races) of the pathogen were identified. Indexes of genetic distances (Nei and Fst) indicated at the changes in the structure of the Derbent population in 2014-2017, when compared with 2008-2011. The long-term dynamics analysis (1970-2017) of P. triticina virulence using 10 TcLr lines revealed certain stability in the Derbent population structure in 1970-2011 and its changes in the subsequent period.