Submitted to: Annals of Applied Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2002
Publication Date: 2/1/2004
Citation: Pipolo, A.E., Sinclair, T.R., Camara, G.M. 2004. Protein and oil concentration response to glutamine in soybean seeds cultured in vitro. Annals of Applied Biology. 144:223-227. Interpretive Summary: Soybean is one of the major crops grown in the United States because it yields a seed very high in protein and oil concentrations. However, these concentrations vary a great deal and the basis for this variation is not understood. In an effort to better explain the basis of variation in soybean seed protein and oil concentrations, a study was undertaken to grow individual soybean seeds under very controlled conditions in the laboratory. This study was done by an ARS-USDA scientist located at Gainesville, FL, and colleagues in Brazil. Very young soybean seeds were excised and placed in nutrient solutions that contained differing concentrations of amino acid. The protein concentration of the seeds grown under these conditions was increased as the amino acid concentration in the solution was increased. Further, the increase in protein concentration was associated with a decrease in oil concentration. These results indicated that a major source of variability in soybean seed composition was the level of amino acid that the mother plant could supply to the developing seeds. This information will help in predicting soybean seed protein and oil concentrations.
Technical Abstract: Oil and protein are the most valuable components of soybean seed. To examine whether oil and protein concentration are affected by the supply of nitrogen to the seed, immature soybean seeds [Glycine max (L.) Merr. cv. Williams 82] were grown in vitro in nutrient solutions containing 20, 40, 60, or 80 mM of glutamine and a sucrose concentration of 204.5 mM. The seeds were incubated in Erlenmeyer flasks for eight days at 25 C. The rate of dry matter accumulation changed from 7.2 to 8.3 mg seed-1 day-1 as the glutamine concentration increased from 20 to 80 mM, but the differences were not statistically significant (P > 0.05). Seed protein concentration increased as glutamine concentration increased from 294 mg g-1 at 20 mM glutamine to as high as 445 mg g-1 at 80 mM glutamine. Typical in vivo protein concentration of mature soybean seeds is about 400 mg g-1. Oil and protein concentration were inversely related (r2 = 0.31). These results indicated that the negative relationship between oil and protein concentration was related to the balance of carbon and nitrogen supply to the seed. Protein synthesis was favored over oil synthesis when nitrogen became more abundant.