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World consumption of soybean (Glycine max) in 2008 was over 221 million metric tons, with approximately 50% of this supply coming from U.S. production, where soybean plantings on an annual basis are over 77 million ha. Soybeans are desired on the marketplace as a valuable source of protein and oil. The former is primarily used as feed, with some food applications, while the latter is more broadly incorporated into food, feed, and some industrial applications (e.g. biodiesel). Protein and oil percentages in soybean, while influenced by both genotype and environmental cues, average approximately 40% and 20%, respectively. A strong indirect phenotypic correlation exists between these traits. In addition, variation in soybean germplasm for protein content is significantly greater than that observed for total oil content. Historically, soybean breeders have used total protein content as a selection criterion for germplasm development. However, recently, both oil content and quality have drawn much attention in soybean genetics and breeding programs, due to the increased demand for vegetable oils and increased consumer awareness of health issues around dietary fats. To this end, significant efforts have been made to increase oxidative stability of soybean oil as a means to avoid trans-fats generated through the hydrogenation process and to enhance v-3 fatty acid content of the oil for use in both food and feed applications and increase the total oil content of seeds.
Commodity soybean prices have risen over 65% during the last decade, from $158.3 per metric ton in June 1999 to $445.2 per metric ton in June 2009. The world demand for soybean is driven by its highly valued protein and oil for use in food, feed, and industrial applications. During embryogenesis, carbon flux in soybean is primarily partitioned between protein and oil, such that at maturity approximately 40% and 20% of the dry matter is in one of these two respective carbon reserves. The remainder of the seed dry matter is largely carbohydrate, which possesses negligible economic value. While some starch accumulates early in embryogenesis, minimal amounts remain at maturity. The inverse relationship between total oil and protein content in soybean is well documented, where typically a 1% reduction in total oil content will lead to a 2% increase in total protein content. Thus, the regulation of...