Induction of Genetic Variants for Soybean Seed Storage Proteins by Mutagenesis

提高大豆种子贮藏蛋白中含硫氨基酸的含量，可以实现大豆种子贮藏蛋白的营养改良。为此，最有效的方法是减少7S球蛋白，这是蛋白质的两种主要成分之一。因此，我们通过γ射线照射大豆品种的干种子，进行了缺乏7S球蛋白α和/或β亚基蛋白的特定突变基因的诱导实验。结果，我们通过40-KR γ射线照射“WASESUZUNARI“的M4种子后代的SDS-PAGE分析，成功地发现了缺乏α和β亚基蛋白的突变基因。结果表明：（1）突变基因的纯合基因型在苗期被黄化病杀死，（2）杂合基因型能正常结实，（3）α和β亚基蛋白质在数量上的正常：中间：缺失的分离比为3：4：1。1.在同一株系中，我们还发现了另一个突变基因，即11 S球蛋白的“组1”亚基（A1、A2、A3的酸性亚基）缺失。该突变基因在一个位点上呈隐性。分离比例为1正常：2中间：1缺乏。纯合基因型（A1、A2和A3缺失）在植株生长中没有表现出异常，并且正常结实。

Nutritional improvement of soybean seed storage proteins can be realized by increase of sulfur-containing amino acid contents in the proteins. For that purpose it is the most efficient to decrease 7S globulin, one of the two major constituents of the proteins. Therefore, we performed induction experiments of a specific mutant gene(s)which lacked alpha and/or beta subunits proteins from 7S globulin by gamma-ray irradiation to dry seeds of soybean cultivar.As a result, we succeeded in finding out a mutant gene which lacked both of the alpha and beta subunit proteins through SDS-PAGE analyses to the M4 seed progenies of 40-KR gamma-ray irradiated " WASESUZUNARI ". We confirmed that(1)the homozygous genotypes of the mutant gene were killed by chlorosis in seedling stage, (2)the heterozygous genotypes were viable and set seeds normally, and(3)the segregation ratio of the normal : intermediate for the alpha and beta subunit proteins in quantity : the lacking for both of the subunits was 3 : 4 : 1.Moreover, we found out another mutant gene which lacked so-called " group 1 " subunits of 11S globulin(acidic subunits of Al, A2, A3)in the same gamma-ray irradiated progenies. This mutant gene worked as a recessive in one locus. The segregation ratio was 1 normal : 2 intermediate : 1 lacking. The homozygous genotypes(Al, A2, and A3 lacking)showed no abnormality in plant growth and set seeds normally.