Development of PCR markers for the wheat leaf rust resistance gene Lr47

The leaf rust resistance gene Lr47 confers resistance to a wide spectrum of leaf rust strains. This gene was recently transferred from chromosome 7 S of Triticum speltoides to chromosome 7 A of hexaploid wheat Triticum aestiv um. To facilitate the transfer of Lr47 to commercial varieties, the complet ely linked restriction fragment length polymorphism (RFLP) locus Xabc465 wa s converted into a PCR-based marker. Barley clone ABC465 is orthologous to the type-I wheat sucrose synthase gene and primers were designed for the co nserved regions between the two sequences. These conserved primers were use d to amplify, clone and sequence different alleles from T speltoides and T aestivum. This sequence information was then used to identify the T speltoi des sequence, detect allele-specific mutations, and design specific primers . Cosegregation of the PCR product of these primers and the T speltoides ch romosome segment was confirmed in four backcross-populations. To complement this dominant marker, a cleavage amplified polymorphic sequence (CAPS) was developed for the 7 A allele of Xabc465. This CAPS marker is useful to sel ect homozygous Lr47 plants from F-2, or backcross-F-2 segregating populatio ns, and in combination with the T speltoides-specific primers is expected t o facilitate the deployment of Lr47 in new bread wheat varieties.