|SHANNON, J GROVER|
Submitted to: American Seed Trade Association Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2006
Publication Date: 12/1/2006
Citation: Vuong, T.D., Pham, A.T., Nguyen, B.T., Hartman, G.L., Miles, M.R., Frederick, R.D., Sleper, D.A., Shannon, J., Walker, D.R., Nguyen, H.T. 2006. Screening US Soybean Germplasm for Rust Resistance. In: Proceedings of the American Seed Trade Association Conference, December 5-8, 2006, Chicago, Illinois. 2007 CDROM.
Technical Abstract: Soybean rust (Phakopsora pachyrhizi Sydow), which has been known as one of the most destructive foliar diseases of soybean in the world, was discovered in the continental United States in November 2004. Rapid spread of the pathogen in Southern and Midwest states increases the potential threat to soybean production in the country. Substantial research advances have resulted from collaborations of national and international institutions aimed at the evaluation of the USDA soybean germplasm collection and exotic germplasm for resistance to the disease. Over 16,500 soybean accessions were initially evaluated in a two-tiered inoculation program at the USDA-ARS BSL-3 containment facility, Ft. Detrick. Of these, 805 accessions with RB lesion or low disease severity were selected for re-evaluations. Subsequently, field and net house tests conducted in Vietnam and Paraguay in two consecutive seasons identified many accessions consistently exhibiting resistant reactions to rust. Other field and greenhouse tests of 778 accessions conducted in Georgia identified many PIs with varied levels of resistance. To further confirm the new sources of resistance, these resistant accessions were tested with ten isolates of rust, including three newly purified isolates from the US. The results showed that these soybean accessions had resistant reactions (RB lesions) or low severity to certain isolates, suggesting that they may have additional resistant genes other than four known dominant Rpp genes or partial resistance. These accessions can be potential sources of resistance for the development of new resistant variety in soybean breeding programs.