Resistance genes against yellow rust pathogen in Triticum spelta: a possible new Yr resistance gene in accession IARI276 and Yr5 presence confirmed in PI348764.

Abstract

Yellow/stripe rust caused by Puccinia striiformis f. sp. tritici is a major biotic stress in global wheat production. Introgression lines derived from the Triticum spelta accessions PI348764 and IARI276 showed high levels of yellow rust resistance at seedling and adult plant stage. The Yr5 gene located on 2B chromosome was previously the only stripe rust resistance gene described in T. spelta gene pool. By genotyping parental and introgressed material with markers linked with the Yr5 gene, we demonstrate that PI348764 likely carries Yr5, and that it appears to be absent from IARI276. By employing a combination of methods, including screening for adult plant resistance and seedling resistance at multiple field trials, bulked segregant analysis (BSA) on F₅ families, and genotyping using wheat Breeders' 35K array, we show that Yr^IARI276 is a novel stripe rust resistance gene with putative chromosomal locations on 1BL, 1DL, 5AL, or 7BL. Furthermore, genetic analysis revealed that Yr^IARI276 showed a goodness of fit to Mendelian ratios for a single dominant gene. As the gene is distinct from Yr5 and the chromosomal location is unique from earlier reported Yr genes, it will be useful in improving diversity of Yr gene repertoire in disease resistance breeding programmes.