Effect of phosphorus on the composition and accumulation of 7S and 11S globulin subunits during seed development of three soybean varieties

Abstract

Three soybean varieties (Dongnong 42, high-protein cultivar; Hefeng 25, medium-protein; and Dongnong 46, low-protein cultivar) grown under different P conditions were investigated in order to evaluate the effect of P on the composition and accumulation of 7S and 11S globulin subunits. The soybean seeds were planted in pots and fertilized with 0.033 g of N and K2O per kg soil. Four levels of P treatment were designed, which were P1, P2, P3 and P4 (i.e., 0, 0.033, 0.067, and 0.100 g of phosphorus pentoxide (P2O5) per kilogram of soil). The composition of extractable proteins was determined by conducting SDS-PAGE. No significant differences were observed between the varieties with regard to the molecular weights of the globulin subunits. After the subunits were formed, their concentrations gradually increased under different P treatments, reached a peak at 70 d post-anthesis (DPA), and then declined during maturity. The concentrations of the 7S and 11S globulins and other subunits in Dongnong 42 and Hefeng 25 were the highest under the P3 treatment, while they were the highest in Dongnong 46 under the P2 treatment. Under the same P treatment, the concentrations were high in Dongnong 42 and low in Dongnong 46 and Hefeng 25. Significant differences were observed in the concentrations of 7S and 11S globulin subunits between the varieties and levels of P treatments, especially under the P3 treatment. Alpha subunit was mainly in relation with the P-nutrition in the three varieties. These findings suggested that the optimal combination of cultivars and P treatment levels could contribute to the increased concentrations of both soybean globulins and their subunits.