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Molecular Characterization and Pyramiding of Novel Scab Resistance Sources Adapted to the Northern Plains Growing Region


To test applicability of family-pedigree based linkage and association mapping techniques commonly used in human genetics to plant breeding populations.

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Approach: We propose to use a novel approach to identify the major loci controlling resistance to FHB in two novel sources of resistance to FHB; SD3934 and Mult757. The proposed approach is based on the method used in human genetics to identify genetic loci controlling genetic disorders in human families. This type of pedigree-based genetic analysis is based on the co-transmission of the phenotypic trait and molecular markers in several families affected by the trait (Jannink and Walsh, 2002). Breeding populations developed by spring wheat program during 2005-2007 which included 83 families consisted of 793 individuals with average family size of 9 members. Resistance to Fusarium head blight was evaluated under greenhouse condition by artifically inoculating a most virulent SDSU isolate. Genotyping was done using mapped markers 3B and other chromosomes. QTL-marker linkage analysis was done using variance component based parametric linkage analysis and pedigree-wide regression. QTL-marker association analysis was done using quantitative transmission disequilibrium test (QTDT) developed for extended pedigrees. All of the approach could map the location of QTL as suggested by previous studies with high probability value. The best fit markers could explain 40-50% of the phenotypic variation. Moreover, QTDT was more stringent to detect markers associated with the QTL. The result shows the usefulness of human genetics the approach to detect relatively large effect QTLs earliest possible in breeding program and subsequent use in MAS. We plan to optimize this approach and use to study the resistance in SD3934.

Walker-Simmons, M. Kay
South Dakota State University
USDA - Agricultural Research Service
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