Brent Hulke, Zahirul Talukder, Lili Qi and Thomas Gulya Jr.
Abstract: In 2010, we continued the process of backcrossing the head rot QTL from the HA 441 x RHA 439 population into confectionery and elite oilseed backgrounds. Progress is slow due to complexities in scoring of alleles in breeding progenies (dominant markers sometimes in repulsion phase, and many gel bands with TRAP). BC2F1 hybrids will be produced this winter. We will again select progeny based on their marker profiles at 6 major QTL loci for advancement into another backcross this next summer. About 50% of the markers are already fixed in the genetic background of the recurrent parent, despite the fact that these lines are susceptible to moderately resistant. We hope that additional QTL will result in more head rot resistant lines by backcrossing. Our efforts to perform association mapping with the 260 Plant Introductions (PIs) obtained from the North Central Regional Plant Introduction Station of USDA-ARS in Ames, IA, are moving forward. We have finished data analysis on the phenotypic data Based on the distribution of data, which is more broadly and normally distributed than we were expecting, we believe that the phenotypes will be adequate for mapping using the association mapping model. We are currently completing the development of a marker set for our resistance candidate genes and 10,000 random SNPs from a companion project. This will contribute the necessary genotypes with which we can complete our association model. As soon as all the genotyping is complete, we can run our association analysis, iscover marker-trait associations for stalk rot, and prepare publications on the work. Our traditional breeding program had a successful season in 2010, with breeding lines in the F4 to F7 selfing generations being tested for Sclerotinia head and stalk rots, each at two locations. Our goal here is to continue introgression of new, minor resistance loci from many domesticated sources into elite germplasm by conventional means. We plan a release of germplasm this winter.
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