Effects of Sulfur Nutritional Forms on Accumulation of Seed Storage Proteins in Soybean(Glycine max)

Effects of Sulfur Nutritional Forms on Accumulation of Seed Storage Proteins in Soybean(Glycine max)

Improvement of seed protein quality might be an essential issue in soybean and would give more profit directly to both farmers and users. This study was carried out to investigate the effects of reduced-S form(s) on seed storage protein components in soybean during seed filling stages. The reduced-S forms during seed fill were sodium thiosulfate, sodium sulfite, sodium sulfide, thioacetate, β-mercaptoethanol, thiourea, thiamine-HCl, L-cysteine, L-cystine, and L-methionine. Seed storage protein concentration did not appear to be affected by any reduced-S forms. However, glycinin and β-conglycinin concentrations seemed to be changed greatly by L-methionine. This resulted in the increase in the 11S/7S ratio(3.58). Among the β-conglycinin, β-subunit was not accumulated at all. α-subunit concentration appeared to be decreased and α -subunit concentration was not altered in comparison with sulfate control. Also, β-conglycine concentration, especially β-subunit concentration, tended to be decreased with L-cystine treatment, resulting in an increase in the 11S/7S ratio(l.83). The glycinin concentration tended to be increased at the expense of the decrease in the β-conglycinin concentration. Therefore, it is suggested that enhancing soybean protein quality would be achieved by improving metabolic pathways of S assimilation in soybean plants during seed filling period under sulfate-sufficient condition.