Effect of ABA application on accumulation of soybean seed storage proteins.A, Immature soybean cotyledons (about 20 mg in fresh weight) were cultured for six days in vitro in control (1.5 mM sulfate) or sulfur deficient (0.03 mM sulfate) medium. Proteins were extracted and subjected to SDS-PAGE analysis. Position of major seed storage proteins, a, a' and b subunits of 7S globulin (b-conglycinin), and acidic (11S-A) and basic (11S-B) subunits of 11S globulin (glycinin) are shown. Accumulation of the b subunit was increased, whereas those of glycinins are reduced. B and C, OAS or ABA was added to the control medium at concentrations shown in the figure. Accumulation of the b subunit was increased by OAS or ABA application, whereas glycinin accumulation was reduced.