Mutations at the glossyl (gll) locus of maize (Zea mays L.) quantitatively and qualitatively affect the deposition of cuticular waxes on the surface of seedling leaves. l h e gll locus has been molecularly cloned by transposon tagging with the Mutafor transposon system. l h e epi23 cDNA was isolated by subtractive hybridization as an epidermis-specific mRNA from Senerio odora (Kleinia odora). l h e deduced amino acid sequence of the GL1 and EP123 proteins are very similar to each other and to two other plant proteins i n which the sequences were deduced from their respective mRNAs. These are the Arabidopsis CERl protein, which is involved in cuticular wax deposition on diques, stems, and leaves of that plant, and the protein coded by the rice expressed sequence tag RICS2751A. All four proteins are predicted to be localized in a membrane via a common NH,-terminal domain, which consists of either five or seven membrane-spanning helices. l h e COOHterminal portion of each of these proteins, although less conserved, is predicted to be a water-soluble, globular domain. These sequence similarities indicate that these plant orthologs may belong to a superfamily of membrane-bound receptors that have been extensively characterized from animals, including the HIV co-receptor fusin (also termed CXCR4).The cuticle is the outermost interface between a plant and its environment, and as such plays a crucial role in the plant's survival (Martin and Juniper, 1970; Kolattukudy, 1981). It consists of cutin embedded in a complex mixture of lipids commonly referred to as the cuticular waxes. Cutin is a polymer of fatty acid derivatives such as w-, di-, and trihydroxy and hydroxy epoxy fatty acids and dicarboxylic fatty acids. These monomers are polymerized by * This work was supported in part by National Science Foundation grant nos. IBN-9316832 intermonomeric ester linkages. Cuticular waxes are a complex mixture of lipids, including hydrocarbons (n-alkanes, branched alkanes, cyclic alkanes, and alkenes), ketones, ketols, alcohols, aldehydes, diols, acids, and esters. The majority of the lipid compounds in the cuticle are derived from cellular fatty acids (for reviews, see Kolattukudy and Walton, 1973; Kolattukudy et al., 1976;Tulloch, 1976; Kolattukudy, 1980). Early biochemical investigations have identified reactions by which many of the various components of the cuticular wax are synthesized (Kolattukudy and Walton, 1973; Kolattukudy et al., 1976;Tulloch, 1976; Kolattukudy, 1980). However, the isolation and characterization of enzymes postulated to be involved in these processes has been technically difficult to achieve because plant epidermal tissue, the site of cuticular wax biosynthesis (Kolattukudy et al., 1976), is difficult to obtain in large quantities. To overcome t h s technical barrier, a molecular genetic approach was taken to isolate a gene involved in cuticular wax biosynthesis. Using the Mutator transposon system, we have cloned the gIossy2 locus of maize (Zea mays L.) via transposon tagging (Chandler and Hard...

The gene for the major protein (WAX9) found in surface wax of broccoli, designated wax9D, and three homologous genes (wax9A, B and C) were isolated from a genomic library using the previously isolated cDNA encoding the WAX9 protein as the probe; all four genes were sequenced. Genomic Southern blot analysis using the WAX9 cDNA as a probe showed the presence of at least four homologous genes in broccoli genome. The sequence of the originally isolated WAX9 cDNA matched with that of gene D. All four genes have an intron two codons before the stop codon. The putative promoter regions of the four genes, beyond the first 200 bp immediately 5' to the translation start sites, are quite different. Essential elements such as TATA and CAAT boxes and several regions homologous to the promoter regions of other plant Itp genes were identified. The expression patterns of the genes were determined by RT-PCR with gene-specific primers and sequencing of the PCR products. All the genes were expressed in leaves and flower buds. While genes A, B and D also were expressed in stems and open flowers, expression of gene C was not detected in these organs. None of them were expressed in roots. The 972 bp 5'-flanking region of wax9D when fused to beta-glucuronidase (GUS) gene, directed tissue-specific GUS expression in transgenic tobacco plants; GUS expression was found in the epidermis of leaves, stems and flower petals, sepals, trichomes, and ovules but not in roots.

No abstract

No abstract

No abstract