title: Expression and distribution of cytosolic 6-phosphogluconate dehydrogenase isozymes in maize.
abstract: Maize (Zea mays L.) cytosolic 6-phosphogluconate dehydrogenase isozymes (EC 1.1.1.44; 6-PGD) are encoded by unlinked loci Pgd1 and Pgd2. Two families from a Robertson's Mutator line were isolated which have no detectable expression of Pgd2. These Pgd2-null mutants and a Pgd1-null line were used to generate plants homozygous for null alleles at both cytosolic 6-PGD loci. The specific activity of 6-PGD in the double-null mutant was between 20 and 30% of wild-type levels in root extracts. The double-null mutant was reproductively viable in a moderate environment, suggesting that wild-type levels of cytosolic 6-PGD activity are not essential for growth. Isozyme dimer ratios in roots, leaves, and scutellum were binomial and reflected the wild-type gene copy number. 6-PGD isozymes showed tissue- and cell type-specific expression.
authors.affiliation: Department of Botany and Plant Sciences, University of California, Riverside 92521.
authors.forename: J
authors.initials: J
authors.lastname: Bailey-Serres
authors.forename: J
authors.initials: J
authors.lastname: Tom
authors.forename: M
authors.initials: M
authors.lastname: Freeling
mesh_terms: D003600:Cytosol / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression; D006720:Homozygote; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010734:Phosphogluconate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics
chemical_list: D007527:Isoenzymes; D010734:Phosphogluconate Dehydrogenase