Dobbels, Austin2016-05-122016-05-122016-03https://hdl.handle.net/11299/180202University of Minnesota M.S. thesis. March 2016. Major: Applied Plant Sciences. Advisors: Seth Naeve, Robert Stupar. 1 computer file (PDF); vi, 103 pages.Mutagenesis has been a useful tool in many crop species to create heritable genetic variability for trait improvement and gene discovery. In this study, fast neutron (FN) radiation was used to induce mutations for studying genes that affect soybean seed composition. Phenotypic screening of the FN population at the University of Minnesota has revealed mutant lines with modified seed protein, oil, and sucrose levels. A significant marker for increased oil was found on chromosome 10 near a known deletion using bulked segregant analysis (BSA). A similar BSA approach was used to characterize FN lines with significantly increased sucrose levels. The elevated sucrose content in the seed will improve flavor of soy based products as well as provide more metabolizable energy in animal feed. These FN lines have approximately 9% sucrose on a dry weight basis compared to the FN parental line, M92-220, which contains approximately 5% sucrose. The progeny of four different outcross populations from these mutants have been evaluated for sucrose content using a colorimetric assay. Overall, the populations vary in sucrose content between 3% and 8% sucrose. The DNA from the tails of the phenotypic distributions for each of the populations were pooled and sequenced for BSA. These studies aim to identify novel marker trait associations and provide molecular markers to be used in breeding programs. Two candidate structural variants found through BSA showed evidence of an association with sucrose levels and warrant further exploration.enThesis or Dissertation