Genomic organization of glycinin genes in soybean.

Glycinin is the predominant seed storage protein in most soybean varieties. Previously, five major genes (designated Gy1 to Gy5) encoding glycinin subunits have been described. In this report two new genes are identified and mapped: a glycinin pseudogene, gy6, and a functional gene, Gy7. Messenger RNA for the gy6 pseudogene is not detected in developing seeds. While Gy7 mRNA was present at the midmaturation stage of seed development in the soybean variety Resnik, the steady state amount of this message was at least an order of magnitude less-prevalent than the mRNA encoding each of the other five glycinin subunits. Even though the amino-acid sequence of the glycinin subunit G7 is related to the other five soybean 11S subunits, it does not fit into either the Group-1 (G1, G2, G3) or the Group-2 (G4, G5) glycinin subunit families. The Gy7 gene is tandemly linked 3' to Gy3 on Linkage Group L (chromosome 19) of the public molecular linkage map. By contrast, the gy6 gene occupies a locus downstream from Gy2 on Linkage Group N (chromosome 3) in a region that is related to the position where Gy7 is located on chromosome 19.