Research Molecular Biologist, Adjunct Professor
USDA-ARS, Division of Plant Sciences
Modification of soybean seed composition and Rhizobium-soybean symbiosis
Modification of soybean seed composition
Soybean is an important source of edible vegetable oil and protein throughout the world and is used in a multitude of food and industrial applications. Even though soybeans are a rich source of protein for livestock and humans, the nutritional quality of soybean proteins is not optimal. Some of the problems associated with soybean proteins include (1) presence of anti-nutritional factors such as trypsin inhibitor, (2) undesirable beany flavor, (3) elicitation of allergic reactions in susceptible individuals (4) poor digestibility of soybean proteins, and (5) deficiency in sulfur-containing amino acids. The goal of our research program is to improve the overall quality of soybean seed composition by molecular biological approaches.
Another area of our research is focused on biological nitrogen fixation using the model symbiosis between soybeans and Sinorhizobium fredii USDA257. Efficient nitrogen fixation greatly enhances the yield of protein-rich seeds. Our research is focused on the molecular basis of host specificity using the model symbiosis between soybeans and S. fredii USDA257. This strain nodulates primitive but not agronomically improved soybean cultivars. Our laboratory is currently focusing on the cultivar-specificity genes of S. fredii. What do they encode? What regulates their expression? And how are the responses are made host specific? Answers to such questions will enable us to rationally manage and enhance the process of biological nitrogen fixation and improve the overall soybean protein quality.