Identification of recombinants carrying stripe rust resistance gene Yr57 and adult plant stem rust resistance gene Sr2 through marker-assisted selection

Many stem rust resistance genes have been formally named in wheat. Adult plant stem rust resistance gene Sr2 was mapped in the short-arm of chromosome 3B. Stripe rust resistance gene Yr57, identified in Aus91463, was mapped about 5cM away from Sr2 based on its linkage with Sr2-linked marker gwm533. The objective of this study was to combine Sr2 and Yr57 in a single genotype. A mapping population containing 107 recombinant inbred lines was developed from a cross between Aus91463-Yr57 and Hartog-Sr2. This population was tested at the seedling stage in the glasshouse for variation in stripe rust response, and high temperature induced Sr2-linked seedling chlorosis. The RIL population was screened for Sr2-linked pseudo black chaff phenotype at the adult plant stage in field. Five recombinants carrying Sr2 and Yr57 in coupling were detected using phenotypic and marker data. Four recombinants also carried leaf rust resistance gene Lr23 from Aus91463. These recombinants are being used as triple rust resistance source in the Australian Cereal Rust Control Program.