Genetic analysis of subunits of two major storage proteins (.BETA.-conglycinin and glycinin) in soybean seeds.

Eight hundred and fifty soybean accessions were screened for genotypes with electrophoretic variations of the β-conglycinin and glycinin subunits. We detected two abnormal SDS-gel electrophoretic forms of β-conglycinin α-subunit, the slow electrophoretic mobility type designated as α-slow-type and the low α-subunit content type designated as α-low-type. Each of these two forms was controlled by a codominant allele at a single locus. The gene symbol Cgy2a was assigned to the common type and Cgy2b to the α-slow-type. We found a new electrophoretic form of β-conglycinin β-subunit designated as β'-subunit which migrates slightly faster than the β-subunit on SDS-gels. Beta-prime (β') subunit was controlled by a single dominant gene designated as Cgy3. The homozygous recessive cgy3 cgy3 lacked the β'-subunit. We observed two variations of the glycinin group-I acidic subunits (A1, A2 and A3) by alkaline urea electrophoresis, i. e., the concomitantly slow and fast electrophoretic mobility types designated as A(I)-slow-type and A(I)-fast-type, respectively. The concomitantly slow and fast migrating Al'A2 and A3 subunits, respectively, behaved in the F2 seeds as a single block composed 'of the three electrophoretic bands. Each of these electrophoretic forms was inherited as if controlled by a codominant allele at a single locus. The gene symbols, Gyla, Gylb and, Gylc were assigned to the alleles for the common electrophoretic type, the A(I)-slow-type and the A(I)-fast-type, respectively. Close linkage was found between Cgy2 and Cgy3. The gene Cgy1 controlling the β-conglycinin α'-subunit was independent of Gy1 and Gy4 which controls the A5 subunit and its associated basic subunit.