Malate dehydrogenase: viability of cytosolic nulls and lethality of mitochondrial nulls in maize.
Five independently inherited loci on five distinct chromosomes encode the mitochondrial and cytosolic isozymes of NAD-dependent malate dehydrogenase (MDH; L-malate:NAD+ oxidoreductase, EC 1.1.1.37). Multiple alleles, including electrophoretic nulls, occur for each locus. However, a single allele of normal activity at one of the three loci encoding the mitochondrial MDHs is sufficient for normal development, whereas plants with essentially no cytosolic MDH activity function normally. The requirement of a normal activity allele at one of the three structural loci encoding the mitochondrial MDHs demonstrates in plants that a commonly studied dehydrogenase enzyme is essential for normal embryogenesis.
D000483:Alleles; D003433:Crosses, Genetic; D003600:Cytosol / Q000201:enzymology; D004247:DNA / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005804:Genes, Lethal; D005838:Genotype; D006720:Homozygote; D008291:Malate Dehydrogenase / Q000235:genetics*; D010944:Plants / Q000201:enzymology*; D003313:Zea mays / Q000201:enzymology
D004272:DNA, Mitochondrial; D004247:DNA; D008291:Malate Dehydrogenase