Genetic Diversity of Soybean (Glycine Max (L.) Merrill)7S Globulin Protein Subunits

Out of 851 soybean accessions from Vietnam, China and Japan analyzed for 7S β-subunit variants, a new β-reduced subunit line with normal growth was collected from the Mekong Delta, Vietnam. Protein of the `β-reduced' line is composed of β-reduced and extremely low-β types. (α-null + β-reduced) type and β-null (or extremely low-β) type were screened in the progeny seeds of the Japanese mutant `(α + β) null' line. Therefore, recombination between α- and β-subunits was identified. By comparing the nucleotide sequence of the partial β-subunit gene of Enrei (standard), Mo-shi-dou Gong 503 (α + β low), β-533 seed (β-reduced), β-57 seed (extremely low-β), and (α + β)-null16((α + β) null) seed, we found that the base `T' at 166 bp, in Enrei changed to `G' in Mo-shi-dou Gong 503, β-533 and β-57. Using the (α + β)-null16 individual as template, a distinct 305 bp β-subunit gene fragment was identified, instead of a 285 bp fragment.