SEQUENCE-ANALYSIS OF THE CLONED GLOSSY8 GENE OF MAIZE SUGGESTS THAT IT MAY CODE FOR A BETA-KETOACYL REDUCTASE REQUIRED FOR THE BIOSYNTHESISOF CUTICULAR WAXES

The gl8 locus of maize (Zea mays L.) was previously defined by a mutat ion that reduces the amount and alters the composition of seedling cut icular waxes. Sixty independently derived gl8 mutant alleles were isol ated from stocks that carried the Mutator transposon system. A DNA fra gment that contains a Mu8 transposon and that co-segregates with one o f these alleles, gl8-Mu3142, was identified and cloned. DNA flanking t he Mu8 transposon was shown via allelic cross-referencing experiments to represent the gl8 locus. The gl8 probe revealed a 1.4-kb transcript present in wild-type seedling leaves and, in lesser amounts, in other organs and at other developmental stages. The amino acid sequence ded uced from an apparently full-length gl8 cDNA exhibits highly significa nt sequence similarity to a group of enzymes from plants, eubacteria, and mammals that catalyzes the reduction of ketones. This finding sugg ests that the GL8 protein probably functions as a reductase during fat ty acid elongation in the cuticular wax biosynthetic pathway.