Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 3, 2011
Publication Date: February 23, 2011
Citation: Krishnan, H.B., Nelson, R.L. 2011. Proteomic analysis of high protein soybean (Glycine max) accessions demonstrates the contribution of novel glycinin subunits. Journal of Agricultural and Food Chemistry. 59:2432-2439. Interpretive Summary: Soybeans, which provide 67% of the vegetable protein and 30% of vegetable oil, are an integral link in the world food chain. Continued improvement in the performance of this crop is vital if increased demand for food by a burgeoning world population is to be met. Presently, soybeans grown in the United States have an average protein content of 40 % but shifts in production to the upper Midwest and continued emphasis on breeding for yield rather than quality threatens to lower this percentage of protein. Development of high-protein soybean lines will facilitate cost efficient production of high protein meals containing at least 48% protein. Currently, limited information is available on the biochemical and genetic mechanisms that regulate high seed protein concentration. In this study, we employed various analytical methods to determine whether the high protein lines preferentially accumulate specific proteins. Our data provides increased knowledge of the variability of protein and protein subunit accumulation among high protein cultivars which will facilitate ongoing efforts to improve the both quantity and quality of soybean seed protein. Increased protein quality will benefit the overall utilization of soybean in the food and feed industries
Technical Abstract: Wisconsin Black, Sioux, PI 82278, PI 340031A, PI 407788A, PI 423948A, PI 437088A, PI 437461, and PI 445845 are soybeans accessions that have seed protein content greater than 50% of the seed dry weight. Currently, very limited information is available on the protein composition of these high protein accessions.Having this information would be useful to begin to determine what genetic differences exist among these accessions and to quantify quality differences. The goal of this study was to identify those proteins responsible for the high protein concentrations in these diverse accessions. SDS-PAGE analysis of seed storage proteins enriched by calcium fractionation revealed significantly higher amount of seed proteins in these accessions when compared with that of soybean cultivar Williams 82. High-resolution two-dimensional gel electrophoretic analysis of seed proteins revealed significant differences among several seed storage protein components in these accessions. A total of 51 protein spots were identified using peptide mass fingerprinting (MALDI-TOF MS). The contribution of these proteins to the overall protein content of the accessions was quantified using Delta2D image analysis software. Results showed that among the majority of the nine accessions, the largest difference in higher protein quantity was within the seed 11S storage globulins. Using 2-DE of three of those accessions, further analysis demonstrated that four proteins in particular were significantly responsible for the higher protein amounts. All four proteins were identified as glycinin subunits. The high protein trait from PI407788A was successfully transferred to an experimental line, LG99-469, demonstrating that this trait was transferable and robust.