Capturing D Genome Variation for Wheat Improvement

The diploid D genome species, Aegilops tauschii Coss. is source of allelic variation for hexaploid wheat, Triticum aestivum L and has provided numerous genes for resistance to diseases and insect pests. Direct crossing of Ae. tauschii accessions with an elite wheat breeding line transferred resistance to the Ug99 races of wheat stem rust. Bulked segregant analysis of BC2F1 genotypes with SSR loci across the D genome identified the chromosome locations of four stem rust resistance genes from four different Ae. tauschii accessions. Fine mapping is underway for a gene located distally on 6D. In the process of gene transfer, a nested design population was developed that samples the D genomes of seven different Ae. tauschii accessions in a single bread wheat background enabling the evaluation of novel quantitative variation. An additional three stem rust resistance genes have been identified this population. Currently, seed dormancy traits, pre-harvest sprouting resistance and amylase activity are being investigated.