Effects of Nutritional Stress on the Storage Proteins of Soybeans

The effects of sulfur deficiency on the complement of proteins laid down in developing seeds of soybean (Glycine max L. Merr) have been examined. Sulfur deficiency caused a 40% decrease in the level of glycinins and a contrasting elevation in the level of beta-conglycinins. The subunit composition of these proteins was also affected. There was in particular a 3-fold increase in the beta-subunit of beta-conglycinins in the sulfur-deficient seeds, and this accumulated largely as the B(0)-isomer of beta-conglycinins, a protein which while virtually devoid of methionine and cysteine retains the physical properties of a normal 7S storage protein. These data demonstrate that a high degree of selectivity can be exerted by environmental stress over the accumulation of proteins in developing seeds.