Inheritance of NADP-active isocitrate dehydrogenase isozymes in soybeans

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Abstract
Eight homozygous Isocitrate dehydrogenase (IDH) zymogram types were observed In the cultivated soybean (Glycine max (L. Merr.) and wild soybean (G. soja Sleb. & Zucc.). The difference observed between zymograms was the consequence of three unlinked loci with variant alleles. The evidence presented indicates there are four active IDH loci in soybeans. Two code for cytosol-associated isozymes. These two loci interact to form Intra- and inter-locus heterodimers, and both have two codominant alleles in the wild and cultivated soybeans examined to date. The remaining two loci code for mitochondrial associated isozymes. Only one of these two was found to be genetically variable with two codominant alleles. The inheritance of the IDH zymogram types represents one of the most complicated systems studied to date in soybeans, because both Inter- and Intra-locus heterodimers were formed, and products of two alleles at different loci had the same electrophoretic migration rate. The most common alleles In G. soja germplasm examined from China, Japan, South Korea, and Russia are Idhi-b (0.985), ldh2-a (0.906), and ldh3-b (0.802). The ldh-a allele was found only in the seed of south Japanese origin, while the ldh2-b was In the seed collected from southern Japan and South Korea. The accessions having these two rare alleles are late maturity groups (V, VI, VII). G. max shows intermediate allele frequencies for all three ldh loci.