Duplicate gene expression for isocitrate dehydrogenase and 6-phosphogluconate dehydrogenase in diploid species of Eleusine (Gramineae)

In the course of a survey of isozyme variation in the grass genus Eleusine, complex band patterns were observed for the enzymes isocitrate dehydrogenase (IDH) and 6-phosphogluconate dehydrogenase (6PGD). These patterns were interpreted as the result of duplicate expression for one of the two genes that ordinarily codes subcellularly compartmentalized forms of each of these enzymes. The interpretation of IDH phenotypes was facilitated by intraspecific allelic variation at one of the putatively duplicated genes (Idh-2), and was verified by examining phenotype ratios in progeny arrays from selfed heterozygotes of E. indica. The lack of analogous intraspecific variation for 6PGD precluded genetic tests, but the duplicate nature of expression was supported by interspecific patterns of variation. Four out of the five diploid species of Eleusine studied (E. indica, E. jaegeri, E. multiflora, E. tristachya) exhibited both duplications; E. floccifolia appeared to lack the IDH duplication, but possessed the 6PGD duplication. Both enzymes showed evidence of hyperduplication in the tetraploid species E. coracana