Suppression of soybean β-conglycinin genes by a dominant gene, Scg-1

Abstract 

β-Conglycinin (7S globulin) is a predominant seed storage protein found in soybean [Glycine max (L.) Merr.]. A spontaneous mutant lacking the β-conglycinin subunits, α´, α and β, has been identified among Japanese wild soybean genetic resources. Although a multigene family encodes the subunits and is distributed in different linkage groups, a single dominant gene, Scg-1 (a suppressor of β-conglycinin), controls the mutant trait. This report characterized the genetic and molecular basis of Scg-1. The null trait was caused not by either structural defects or changes in the β-conglycinin subunit genes, but by a lack of transcription of the genes, indicating that Scg-1 suppresses expression of all the structural genes. Linkage analysis revealed that the Scg-1 locus was located in the same chromosomal region as the α and β subunit genes, which are tightly linked to each other. Furthermore, the methylation of the chromosomal region containing the Scg-1 and α and β subunit loci was observed, suggesting that the deficiency is associated with the silencing of multicopy genes. Scg-1 had no obvious effect on the plant growth, so it will be a useful gene source for manipulation of the protein composition in soybean seeds.