Fast Neutron Induced Structural Variants and Seed Composition in Soybean Lines.

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 effect 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.  Previously, a significant marker for increased oil was found on chromosome 10 near a known deletion using bulked segregant analysis (BSA).  A similar BSA approach is underway 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 compared to the FN parental line, M92-220, containing approximately 5% sucrose.  The progeny of four different outcross populations from these mutants are being evaluated for sucrose content using a colorimetric assay.  Preliminary results show a distribution ranging from 3- 8% sucrose in the first population screened.  The DNA from the tails of the phenotypic distributions will be pooled and sequenced for BSA.  These studies will identify novel marker trait associations and provide molecular markers to be used in breeding programs.