| Soybean [Glycine max (L.) Merr.] is the most important grain legume in the world as well as in the United States. Wild soybean, Glycine soja Sieb. and Zucc., is considered the ancestor of G. max and together they form the primary gene pool for soybean. Maintaining and evaluating annual Glycine soybean germplasm, and identifying and exploiting new genes in this germplasm are critical for the future success of soybean cultivar development.; In order to quantify genetic variation within G. soja, G. max and semi-wild accessions and to investigate the relationships among these three types, ninety-two accessions of semi-wild, G. soja and G. max from the USDA Soybean Germplasm Collection were evaluated for 20 phenotypic traits and with RAPD markers. The results demonstrated that three phenotypical characters were most important in distinguishing among these three types and OPG11-072500, OPO01-04700 and OPO01-06850 are unique bands for semi-wild, G. max and G. soja, respectively, for the accessions tested.; To identify the variation for plant height at early growth stages in G. soja accessions and to begin a genetic analysis of this variation, five accessions were selected within each of three maturity groups (00, II and IV) to represent three height classes, tall, intermediate and short, based on the data collected in 1999. The results from a replanted test in 2000 demonstrated the difference for mean height of each class within maturity groups was significant and this difference was not related to maturity group.; One white-flowered plant was found in G. soja accession PI 424008A growing in Stoneville, Mississippi in 1998. In order to clarify the origin of this white-flowered plant, phenotypic traits, and RAPD and SSR markers were used to compare the white-flowered line with the putative parental line PI 424008A. The results from all of the data show that the white-flowered plant is 98% similar to PI 424008A. These data would indicate that the white-flowered plant was produced by a mutation in PI 424008A.; We conducted research on evaluating and classifying the variation of the leaflet shape and size in the USDA Soybean Germplasm Collection and determining the genetic control of leaflet shape in G. soja. The F 2 progenies of eight G. max x G. soja and G. soja x G. soja crosses indicate at least two new loci controlling leaflet shape in G. soja. (Abstract shortened by UMI.)... |
