Structural Variation Around the Gene Encoding the .ALPHA. Subunit of Soybean .BETA.-Conglycinin and Correlation with the Expression of the .ALPHA. Subunit.

We have identified two genes, located approximately 2.5 kb apart in the soybean genome, that are closely related to the α subunit of β-conglycinin. One of these genes has been shown to encode the α subunit and the other is very similar to the α subunit gene (referred to as the “ α-related gene”). To determine whether the latter α-related gene expresses the α subunit, the structure of the chromosomal DNA region that contains the two genes was compared among soybean varieties exhibiting different expression levels of the subunit protein. We observed the presence of deletions of the α subunit and α-related genes in some varieties. In the naturally occurring variety Keburi, which accumulates the α subunit protein, the entire α-related gene was deleted in addition to the previously known deletion of the α′ subunit gene. On the contrary, the α subunit gene was deleted in Moshidou Gong 503 and Kari-kei 434. These structural analyses revealed that the α-related gene expresses the α subunit at least in Moshidou Gong 503 and Kari-kei 434. These two varieties do not harbour the α subunit gene, but carry the intact α-related genes and still express the α subunit.