Identification and Characterization of Sr59-Mediated Stem Rust Resistance in a Novel Wheat-Rye Translocation T2BL.2BS·2RL

Authors: YAZDANI, MAHBOOBEH - Swedish University Of Agricultural Sciences; Rouse, Matthew; BAJGAIN, PRABIN - University Of Minnesota; Danilova, Tatiana; MOTSNYI, IVAN - National Agrarian University - Ukraine; STEFFENSON, BRIAN - University Of Minnesota; PATPOUR, MEHRAN - Aarhus University; RAHMATOV, MAHBUBJON - Swedish University Of Agricultural Sciences

Submitted to: The Crop Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2025
Publication Date: 6/1/2025
Citation: Yazdani, M., Rouse, M.N., Bajgain, P., Danilova, T.V., Motsnyi, I., Steffenson, B.J., Patpour, M., Rahmatov, M. 2025. Identification and Characterization of Sr59-Mediated Stem Rust Resistance in a Novel Wheat-Rye Translocation T2BL.2BS·2RL. The Crop Journal. 13(2025) 909-918. https://doi.org/10.1016/j.cj.2025.02.012.
DOI: https://doi.org/10.1016/j.cj.2025.02.012

Interpretive Summary: Stem rust is historically a major disease of wheat in the United States and around the world. Newly emerged strains of this pathogen, such as Ug99, have developed virulence to most deployed stem rust resistance (Sr) genes. A recently described wheat stem rust resistance gene was effective to Ug99 and other emerging strains named Sr59. We backcrossed Sr59 into adapted wheat backgrounds to make this gene more accessible in wheat breeding programs. This study will enable U.S. wheat breeders to develop new varieties with Sr59 stem rust resistance to prevent yield losses caused by new strains of the stem rust fungus. This will help secure the U.S. wheat crop.

Technical Abstract: Emerging new races of wheat stem rust (Puccinia graminis f. sp. tritici) are threatening global wheat (Triticum aestivum L.) production. Host resistance is the most effective and environmentally friendly method of controlling stem rust. The stem rust resistance gene Sr59 has beenwas previously identified within a T2DS·2RL translocation, providing broad-spectrum resistance to various stem rust pathogen races. This study aimed to identify a shortened version of the 2RL chromosome segment containing Sr59, map its physical location accurately, and develop a robust molecular marker for marker-assisted selection. Seedling evaluation, molecular marker analysis, and cytogenetic studies identified line #284 as having a new wheat-rye T2BL.2BS·2RL translocation containing the Sr59 resistance gene. This translocation has also demonstrated broad-spectrum resistance to stem rust at the seedling stage, indicating its potential for effective protection against various races. Seedling evaluation and cytogenetic analysis of three backcross populations between line #284 and the adapted cultivars SLU-Elite, Navruz, and Linkert confirmed that the Sr59 stem rust resistance gene is stably located within the T2BL.2BS·2RL translocation. Using genotyping-by-sequencing (GBS), the study aligned GBS-derived SNPs with full-length annotated rye nucleotide-binding leucine-rich repeat (NLR) genes in the parental lines CS ph1b, SLU238, SLU-Elite, Navruz, and Linkert, as well as in 33 stable BC4F5 plants (11 from each backcross population). Four NLR genes were identified on the 2R chromosomeintrogression, one of which is associated with resistance to Sr59-mediated stem rust . Using genotyping-by-sequencing (GBS), the study aligned GBS-derived SNPs with full-length annotated rye nucleotide-binding leucine-rich repeat (NLR) genes in the parental lines CS ph1b, SLU238, SLU-Elite, Navruz, and Linkert, as well as in 33 stable BC4F5 plants (11 from each backcross population), identifying four NLR genes on the 2R chromosome, one of which is associated with resistance to Sr59-mediated stem rust. These findings provide robust molecular markers for wheat breeding programs and offer a better understanding of the genetic basis of Sr59 resistance.