Genetic control of glutamate oxaloacetate transaminase isozymes in the diploid plant Stephanomeria exigua and its allotetraploid derivative

Abstract

The multiple forms of glutamate oxaloacetate transaminase in the annual diploid plant Stephanomeria exigua (Compositae) are controlled by three unlinked gene loci with two, four, and five alleles, respectively. All alleles are codominant, and heterozygotes for any pair of them produce a more darkly staining enzyme with intermediate mobility, suggesting that the enzymes have a dimeric subunit structure. In natural populations, the same allele is predominant or fixed at each locus. Stephanomeria elata, the allotetraploid derivative of S. exigua and the closely related S. virgata, produces multiple enzyme variants coded by one pair of its duplicated loci which are identical in electrophoretic mobility to those of diploid individuals heterozygous at this locus. The formation of multiple enzyme variants in all individuals of the tetraploid may provide a degree of biochemical versatility that contributes to its ability to colonize disturbed habitats.