Duplicated cytosolic malate dehydrogenase genes in Zea mays.

Six inbred lines of Zea mays expressing different soluble (cytosolic) malate dehydrogenase (sMDH) zymogram phenotypes were analyzed genetically. sMDH was found to be coded for by unlinked duplicated loci in four of these inbred lines. The remaining two lines were found not to possess these duplicated loci. Furthermore, the duplicated loci, sMdh1 and sMdh2, have been found to be located on different chromosomes: sMdh1 on chromosome 1L linked to Amp1, and sMdh2 on chromosome 5S linked to Cat1 and Amp3. The importance of finding sMDH encoded by duplicated loci is discussed in relation to the role of chromosomal rearrangements, the relationship between the cytoplasmic and mitochondrial enzymes, and the evolution of Z. mays.