Inheritance and linkage relationships of 6-phosphogluconate dehydrogenase isozymes in soybean
The inheritance of 6-phosphogluconate dehydrogenase (6-PGD) in dry seeds of cultivated and wild soybean was studied electrophoretically. There are four 6-PGD anodal bands that are controlled by three loci. Bands 1 and 3 are homodimers, whereas band 2 is the interlocus heterodimer of bands 1 and 3, which are products of the Pgd1 and Pgd2 loci, respectively. Both Pgd1 and Pgd2 loci have three codominant alleles (Pgd1-a, Pgd1-b, Pgd1-c and Pgd2-a, Pgd2-b, Pgd2-c) and each of the alleles specifies an isozyme band. The two variants of the fourth band are the result of two codominant alleles (Pgd3-a and Pgd3-b) of the Pgd3 locus. The Pgd3-a allele is found only in PI486.220, a Glycine soja accession from Japan. The Pgd2 is linked to Ap, Ti, and Lap1 in the order of Ap–Ti–Lap1–Pgd2 and belongs to linkage group 9. Key words: soybean isozymes linkage, genetics of Pgd loci.