Characterization of Introgressive Spring Bread Wheat Lines for Stem Rust Resistance (Including Race Ug99), the Presence of Sr Genes, and Agronomically Valuable Traits
Abstract
This paper presents the results of evaluating 128 introgressive spring bread wheat lines developed at the Federal Agricultural Research Center of the South-East for resistance to race Ug99 (TTKSK) of the stem rust pathogen Puccinia graminis f. sp. tritici and its biotypes under natural infection pressure at the Kenya Agricultural Research Institute (KARI). As a result of the evaluation, 26 lines were identified that combine immunity (10 lines) or moderate resistance (16 lines) to Ug99 with field resistance to the Saratov pathogen population and seedling resistance to Russian populations of P. graminis f. sp. tritici. Using molecular markers, the effective resistance genes Sr25, Sr28, and Sr35 were identified in the Ug99-resistant lines, in combinations Sr25 + Sr31, Sr25 + Sr28, and Sr25 + Sr35. The results of virulence analysis of Russian P. graminis f. sp. tritici populations from 2017–2025 confirm that race Ug99 has not yet been introduced into the Volga region, and the Sr31 gene remains the most effective against local populations. The main drawback of the resistant introgressive lines is reduced grain yield; however, lines with increased yield were identified. Furthermore, in terms of Chopin alveograph parameters, grain protein content, and gluten quantity and quality, most introgressive lines were not inferior to or surpassed the standard variety Saratovskaya 76. Thus, the identified lines, resistant to both Russian stem rust populations and race Ug99, represent valuable initial material for breeding for immunity to this dangerous disease.