Mutant Strains with Low Level of Subunits of 7S Globulin in Soybean (Glycine max Merr.) Seed

Abstract

By screening about 1700 soybean strains using sodium dodecyl sulfate polyacrylamide gel eledtrophoresis, two strains were found to have low levels of 7S-subunits (α, α' and β) : the amounts of α- and β-subunits in Mo-shi-dou (Gong 503) soybean seeds were about one half to one third of those found in normal soybean seeds, and the α'-subunit was not detected in Keburi soybean seeds. Mo-shi-dou (Gong 503) and Keburi soybean seeds were found to have high 11S/7S ratio, or 2. 59 and 1.61 respectively, compared with an average value of 1.12 of those of the four normal strains, Amsoy, Norin No.2, Sakagami No.2 and Raiden, by the disc gel electrophoresis. However, the two mutant strains showed similar levels of protein content compared with those of the normal strains. This indicates that it should be possible to increase 11S/7 S ratio without decreasing the protein content in soybean seeds. The average amount of the total sulfur-containing amino acids (cystine+methionine) of the two mutant strains was about 1.2 times higher than that of the four normal strains.