Development of PCR markers for 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 7S o f Triticum speltoides to chromosome 7A of hexaploid wheat Triticum aestivum . To facilitate the transfer of Lr47 to commercial varieties, the completel y linked restriction fragment length polymorphism (RFLP) locus Xabc465 was converted into a PCR-based marker. Barley clone ABC465 is orthologous to th e type-I wheat sucrose synthase gene and primers were designed for the cons erved regions between the two sequences. These conserved primers were used to amplify, clone and sequence different alleles from ir: speltoides and T. aestivum. This sequence information was used to identify the T. speltoides sequence, detect allele-specific mutations, and design specific primers. C osegregation of the PCR product of these primers and the T. speltoides chro mosome segment was confirmed in four backcross-populations. To complement t his dominant marker, a cleavage amplified polymorphic sequence (CAPS) was d eveloped for the 7A allele of Xabc465. This CAPS marker is useful to select homozygous Lr47 plants from F-2 or backcross-F-2 segregating populations, and in combination with the T- speltoides specific primers is expected to f acilitate the deployment of Lr47 in new bread wheat varieties.