Project Number: 5366-21000-028-03
Project Type: Specific Cooperative Agreement

Start Date: Aug 09, 2006
End Date: Jul 31, 2010

Objective:
Deploy effective stripe rust resistance genes in the next generation of U.S. barley varieties, including germplasm from the ARS-Aberdeen breeding program. Complementary marker assisted selection (MAS) and phenotypic selection procedures will be used.

Approach:
Genes conferring quantitative resistance to barley stripe rust have been mapped and their effects validated, individually and in various combinations, in a "Baronesse" background. These resistance genes have been shown to be effective against a range of races and in a range of environments from Peru to Washington State. Scientists at Oregon State University have also developed a near-isogenic line of Baronesse with a major gene on chromosome 7H. This major gene should be deployed only in conjunction with the quantitative resistance alleles. Breeders from the state university and ARS barley programs in California, Idaho, Montana, and Washington (representing the regions at greatest risk to stripe rust) will be invited to provide an elite line (or variety) for resistance gene introgression. Breeders from the private sector programs in the region (Busch Agricultural Resources, Coors, and Westbred) will also be invited to submit lines and to join the consortium as contributing members. We will cross these lines/ varieties with the quantitative and qualitative resistance stocks. The resistance genes have been mapped in doubled haploid populations based on a limited number of crosses. Therefore, we are lacking essential information on the degree of dominance of the resistance genes and the effects of the target genetic backgrounds on resistance gene expression. We do have data on the individual and joint effects of resistance genes on quantitative resistance phenotypes (latent period, lesion size, etc.) and we have evidence for significant positive and negative genetic background effects on the level of resistance conferred by introgressed genes. Therefore, the first steps in the process of resistance gene transfer will be to determine the degree of dominance, background effects, and the individual vs. joint effects of resistance genes. These characteristics will be measured on a subset of the possible F1 combinations, using the four most genetically diverse target backgrounds. The three-QTL pyramid and the qualitative resistance gene will be transferred to all backgrounds and will be targeted for phenotypic and marker assisted selection in subsequent cycles.