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Improving the Protein Content of Soybeans

Improving the protein content of soybeans is an objective in most soybean breeding programs. Researchers at the University of Missouri are using exotic germplasm from Nepal as a resource in their efforts to improve the protein and amino acid content of soybean varieties. Several cultivars from Nepal with about ten percent more protein are being tested to determine differences in the protein profile compared to U.S. germplasm lines. High-resolution two-dimensional gel electrophoresis revealed major differences in various isoelectric forms of glycinin and beta-conglycinin storage proteins in these cultivars. Using molecular analytical tools, the researchers found differences in genes controlling these storage proteins and for Bowman-Birk protease inhibitors. Further studies indicated the Nepalese soybean lines contained 5-10 percent more arginine and two cultivars contained significantly more cysteine than the U.S. reference variety. The importance of this research is that these high-protein Nepalese soybean cultivars provide additional diversity for soybean breeders to use in developing soybean lines with higher levels of protein with improved amino acid quality. Further more, it is encouraging to know that the amino acid levels in soybean storage proteins are variable in nature. This offers hope that amino acid levels can be changed in storage proteins without major structural and functional impact to the soybean plant.

Krishnan, H.B. and co-workers. 2006. Assessment of indigenous Nepalese soybean as a potential germplasm resource for improvement of protein in North American cultivars. J. Agric, and Food Chem. 54(15): 5489-5497.