| Abstract
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Avena sterilis L., the putative wild-weedy hexaploid progenitor of cultivated oat (A. sativa L. and A. byzantina C. Koch) is a valuable source of genetic variation for cultivar improvement. A better understanding of relationships between A. sterilis and the cultivated gene pool, and an intensive evaluation of backcross populations involving A. sterilis and A. sativa could improve the utilization of over 8,400 wild accessions stored in the US National Small Grains Collection. The objectives of this research were: (1) to compare relationships among a sample of 96 genetically and geographically diverse A. sterilis accessions and 24 historically prominent oat cultivars based on RAPD marker variation, linkage disequilibrium analysis and the distribution of the 7C-17 intergenomic chromosomal translocation; (2) to evaluate the breeding potential of the A. sterilis germplasm clusters identified by isozyme and RAPD analyses in backcross populations with contemporary U.S. winter oat cultivars, and (3) to identify RAPD markers of exotic origin associated with agronomic and seed quality traits in backcross derived lines. The results from RAPD, linkage disequilibrium and the 7C-17 chromosomal translocation analyses found a close relationship between cultivated accessions and A. sterilis accessions from Iran, Iraq and Turkey. Two, or more independent lines of descent from A. sterilis were hypothesized; one from A. sterilis containing the 7C-17 translocation and another from A. sterilis without the 7C-17 translocation. The occurrence of significant differences among cluster means for grain yield biomass, harvest index, test weight, heading date, plant height, protein content and freeze damage suggested that sampling accessions based on isozyme or RAPD analyses would be an effective method on which to initiate evaluation of the breeding potential of the wild oat collection. QTLs in BC2F plants were associated with grain yield, biomass, straw weight, harvest index, test weight, kernel weight, protein content, plant height, and freeze damage in BC2F-derived lines. The interactions of QTLs with environments were significant for all traits. There were more QTLs of exotic origin which increased grain yield, biomass, harvest index, straw weight and test weight than those which decreased them.
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