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...

Sequences homologous to a potato cathepsin D inhibitor cDNA, p749, were identified in the genomic DNA of tomato (Lycopersicon esculentum) and of two non-tuber-bearing potato species (Solanum etuberosum and S. brevidens) by means of Southern blot analysis. The expression of these p749 genes in leaves was induced at the RNA level in response to wounding. High levels of p749 transcripts were detected in polyadenylated RNA extracted from locally wounded leaves 12 h after wounding. Systemic induction of the cathepsin D inhibitor gene also occurred in nonwounded leaves of wounded plants. Both potato and tomato leaves treated with the oligosaccharide chitosan showed an induced accumulation of p749 transcripts. Even though the cathepsin D inhibitor genes from tomato and from non-tuber-bearing potato species are wound inducible, they could not be induced in leaf explants cultured on medium containing very high concentrations of sucrose. Only leaf explants from the tuber-bearing potato (S. tuberosum) accumulated p749 transcripts when cultured on high sucrose medium. A sequence related to the 22-kD potato proteinase inhibitor cDNA, p34021, was identified in tomato by means of genomic Southern blot analysis. Northern blot hybridization showed that p34021 transcripts accumulated in potato (S. tuberosum) leaf explants, but not in tomato explants, when cultured on high sucrose medium. This study demonstrates that the expression of a potato cathepsin D inhibitor gene in tomato and in non-tuber-bearing potato species is wound inducible, but not sucrose inducible.

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