Location: Plant Genetics Research2011 Annual Report
1. Soybean storage protein accumulation is not regulated by glutamine synthase. While glutamine synthatase (GS) is known to be a key regulatory enzyme for nitrogen metabolism and thus protein synthesis in leaves, relatively little is known about the role it plays in seed development and storage protein accumulation. Results developed by an ARS scientist in Columbia, MO from quantitative analyses of GS transcripts, catalytic activity, levels of substrates and products, and organ, tissue, and cellular localization were added to the systems model of soybean seed development that is used to predict how seed composition is altered by environmental conditions or genetic manipulation through breeding. There is a surprising discordance between GS and the abundant seed storage proteins, indicating that this particular enzyme is unlikely to have a regulatory role in seed development and would not be a good target for genetic or biotech-based manipulations aimed at increasing seed protein levels, a key target to improve soybean meal for live stock consumption.
2. Novel glycinin subunits contribute to high seed protein soybean accessions. Soybeans grown in the United States presently have an average protein content of 40%, however shifts in production to the upper Midwest and continued breeding emphasis on yield rather than quality threaten to lower this value. Lowering the protein content of U.S. soybeans would reduce their competitive value in the global market place and reduce the price that the farmer receives. The development of high-protein soybean lines will facilitate cost-efficient production of seed meal containing at least 48% protein, maintaining and possibly improving market values for U.S. soybeans. Because limited information was available to define the biochemical and genetic mechanisms that regulate seed protein concentration, an ARS scientist in Columbia, MO has developed analytical methods to determine if the high protein lines preferentially accumulate specific protein species. Results using high-resolution two-dimensional gel electrophoresis indicate that the most prominent difference that characterized high-protein accessions was attributed to the 11S seed storage proteins, the glycinins. These data will facilitate efforts to increase both quantity and quality of seed protein, which will increase utilization of soybeans by the food and feed industries.
3. An alternate means developed to produce soybeans containing high oleic acid oil. Soybeans are a commodity crop that provides a major component of fats and oils in the American diet. Typically around 20% of soybean seed oil is oleic acid, however an increase in oleic acid would be desirable because of the resultant health benefits. High oleic acid also increases oxidative stability and extends the utility of soybean oil at high temperatures. Genetically changing soybean oil from 20% to greater than 55% oleic acid would allow wider use of soybean oil in food, pharmaceuticals, cosmetics, biodiesel and industrial lubricant applications. An ARS scientist in Columbia, MO, developed a genetic strategy for producing soybean varieties with high oleic acid oil using genes from the soybean germplasm collection. This alternative method resulted in oil with over 80% oleic acid content, and is an important complement to existing high oleic acid-soybeans produced using a biotechnology strategy. Soybeans produced in this way will improve the competitiveness and value of U.S. soybeans, directly impacting the soybean and food industries.Bilyeu, K.D., Gillman, J.D., Leroy, A. 2011. Novel FAD3 mutant allele combinations produce soybeans containing 1% linolenic acid in the seed oil. Crop Science. 51:259-264.