Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2009
Publication Date: 4/20/2010
Publication URL: http://hdl.handle.net/10113/43379
Citation: Mikel, M.A., Diers, B.W., Nelson, R.L., Smith, H.H. 2010. Genetic Diversity and Agronomic Improvement of North American Soybean Germplasm. Crop Science. 50:1219-1229. Interpretive Summary: Proprietary soybean varieties dominate the production area in the U.S. Little information has been available about the pedigrees of these varieties and the change in genetic diversity of the soybean crop since varieties developed by private companies have become so important in U.S. agriculture. Using public records of patents, plant variety protection certificates and registrations in scientific journals, we have created and analyzed the pedigrees of over 2,200 varieties of both public and private origin that were released between 1970 and 2008. The most commonly used parent, Williams, is the direct parent of more than 70 varieties. We found that the gene pool of private companies and public programs are very similar and most cultivars are in one of three major genetic groups. Based on reported data, seed yield has increased at the rate of 3.2% per breeding cycle. This information will be useful to soybean breeders to help manage the genetic diversity in breeding programs.
Technical Abstract: From 1970 to 2008 there were 2,242 soybean cultivars registered in North America through U.S. PVP, U.S. utility patent, and journal registration. Of these, 80% were developed through proprietary and 20% through public programs. The most frequently used germplasm for cultivar development were the cultivars ‘Williams’ (parent used in last cross prior to inbreeding in 70 cultivars), ‘A3127’ (63), ‘Essex’ (45), ‘Amsoy’ (38), ‘Corsoy’ (33), ‘Wayne’ (30), ‘Forrest’ (27), ‘Hutcheson’ (25), ‘MO13404’ (23), and ‘Bedford’ (23). Genetic Diversity (1 – coefficient of parentage), estimated from pedigree lineage, was 0.89 overall. Genetic diversity was the same within public (0.89) and proprietary (0.89) developed cultivars. The cultivar A3127 is a major progenitor of recently developed proprietary cultivars registered from 1999 to 2008. Of these 494 cultivars, half have a genetic contribution of at least 10% from A3127. New cultivars were predominately developed from the following crosses: 2-parent (70% of cultivars developed), complex (12%), 3-parent (5%), one backcross (5%), multiple (2, 3, or 4) backcrosses (3%), and backcross 5 or greater (2%). Approximately 1% of the cultivars were from selections within cultivars, broad base populations and mutation selections. In comparisons where both parent and progeny were evaluated in the same environments, seed yield increased 3.2% per breeding cycle. In these comparisons, seed yield had a correlation of 0.29 with parental diversity.