Development of a PCR Assay and Marker-Assisted Transfer of Leaf Rust and Stripe Rust Resistance Genes Lr57 and Yr40 into Hard Red Winter Wheats Adapted to Southern Great Plains.

The wheat-Aegilops geniculata introgression T5DL·5DS-5M^gS(0.95), with stripe rust resistance gene Yr40 and leaf rust resistance gene Lr57, is an effective source of resistance against most isolates of the rust pathogen in Kansas and India. Rust resistance genes Lr57 and Yr40 were transferred to the hard red winter wheat (HRWW) cultivars Jagger and Overley by standard backcrossing and marker-assisted selection (MAS). PCR-based cleaved amplified polymorphic sequence (CAPS) markers were developed and used to select backcross F₁ plants with rust resistance. Diagnostic polymorphism detected by CAPS marker XLr57/Yr40-MAS-CAPS16 was consistent between the resistant source and a set of wheat cultivars selected by the US Wheat Coordinated Agricultural Project (CAP). Homozygous BC₃F₂ plants with rust resistance genes were selected using the RFLP-based diagnostic DNA marker polymorphism detected by the wheat grain softness protein (Xgsp). Deletion of Puroindoline a (Pina-M^g1) and Puroindoline b (Pinb-M^g1) gene sequences in the chromosome segment of 5M^gS substituting for 5DS of wheat suggests that the backcross derivatives with Lr57/Yr40 can be used to develop hard textured-wheats. HRWW germplasm with Lr57 and Yr40 will provide breeders in the SGP with adapted lines having an additional source of resistance that can be used to develop durable rust resistance either by gene deployment or gene pyramiding