Fine Mapping of Stripe Rust Resistance Gene Yr15 in Durum Wheat

Stripe rust is one of the most important fungal diseases of wheat that has been reported in all continents and more than 60 countries in the world. Wild emmer wheat,Triticum dicoccoides, the tetraploid progenitor of cultivated wheat, has proven to be a valuable source of novel stripe rust resistance genes for wheat breeding. G25 accession of this species has Yr15 gene that confers resistance to 31 stripe rust races and pathotypes. It has been mapped on chromosome 1BS. In the present study, as a first step towards map-based cloning of Yr15, it was fine-mapped in a F2 population with 825 individuals. According to frequency of retrotransposons in euchromatin regions of the genome and near the gene cluster, retrotransposon-based molecular markers were mostly used. Three SSR, three IRAP and seven REMAP markers were identified to be linked to the gene with a distance less than 2 cM and genetic map near the gene was saturated. Some markers were cosegragated at proximal side of the gene. One of the IRAP and two REMAP markers converted to locus specific and codominant SCAR markers. Locus specific and codominat marker, SC792, completely co-segragated with gene. Other two locus specific and codominant markers, SC1600 and SC1028, surrounded the gene in an interval of
1 cM. These markers could be used for reliable MAS and map-based cloning of Yr15. Also, it was demonstrated that retrotransposon based markers can be more useful and efficient in fine-mapping of genes controlling agronomically important traits.