Identification of leaf rust resistance genes in the new Russian varieties of common wheat

Background. Wheat leaf rust caused by Puccinia triticina Erikss. is a significant wheat disease in all regions of the Russian Federation. The genetic diversity of the cultivated wheat varieties regarding the type of resistance and genes that control it ensures reliable protection of this crop against the pathogen. The aim of this work was to characterize the diversity of new Russian varieties of winter and spring common wheat for leaf rust resistance genes (Lr-genes).Materials and Methods. The research material was represented by 43 varieties of winter and 25 of spring wheat included in the State Register of Selection Achievements of the Russian Federation in 2018-2020.Results. Using molecular markers, 18 Lr genes were identified: Lr1, Lr3, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, Lr25, Lr26, Lr28, Lr29, Lr34, Lr35, Lr37, Lr41 (39), Lr47 and Lr66. A phytopathological test was used to clarify the results of molecular analysis. Ninety-three percent of the studied wheat varieties were found to contain Lr genes, either separately or in combinations. These were the highly and partially effective genes Lr24, Lr9, and Lr19, adult plant resistance genes Lr34 and Lr37, and ineffective genes Lr1, Lr3, Lr10, Lr20, and Lr26. The Lr24 gene has been identified for the first time in Russian varieties. The spring variety ‘Leader 80’, harboring this gene, is recommended for cultivation in the West Siberian and East Siberian regions. An effective combination of Lr9 + Lr26 genes, individually overcome by the pathogen, was determined in the spring cultivar ‘Silach’, highly resistant to leaf rust. The Lr9 gene was found in the winter variety ‘Gerda’, which is recommended for cultivation in the North Caucasus region. Previously, the varieties with Lr9 were not grown in the North Caucasus. An increase in the number of leaf rust resistant accessions protected by the effective adult plant resistance gene Lr37 is noted among wheat varieties undergoing regional adaptation testing. Many of the identified Lr genes (Lr19, Lr24, Lr26, Lr34, Lr37) are linked with effective Sr genes (Sr25, Sr24, Sr31, Sr57, and Sr38), which additionally ensures stable genetic protection of wheat against stem rust.Conclusions. The obtained information about representation of Lr genes in wheat varieties should be used in regional breeding programs. A timely replacement of genetically protected varieties allows stabilizing the populational composition of the phytopathogen and reducing the likelihood of epiphytotics.