Ethylene has been implicated as a sex-determining hormone in cucumber. Its exogenous application increases femaleness,and gynoecious genotypes were reported to produce more ethylene. 1-aminocyclopropane-1-carboxylate (ACC) oxidase(ACO) is the key enzyme in ethylene biosynthesis. In this study, a 1200 base pair (bp) candidate fragment was amplifiedfrom the cucumber genome with degenerated primers derived from the ACO amino acid consensus sequence amongdifferent plant species. The coding region and its upstream (1 155 bp) were obtained by vector-mediated inverse PCR. Thenovel gene was analyzed by bioinformatics tools. Four exons and three introns were identified in the coding sequence.The spliced length of mRNA was 933 nucleotides (nts) and it encoded 311 amino acids. Phylogenic analysis result of thenew gene (CsACO4, GenBank accession number AY450356) was in accordance with the evolution relationship of geneticsamong various plant species. Northern blotting showed that the gene expressed among female flowers of gynoecious andmonoecious genotypes, it could not express in other organs. This implied that the gene might be correlated with the femalebehavior positively. Further work is on the way to demonstrate the complexity of the relationship between the endogenousethylene and the sex determination.
A fragment of 2000 bp upstream sequence of Ell clone was amplified from genomic DNA of the tomato cultivar Zhongshu- 5. Sequence analysis showed that the upstream contains the regulatory elements： TATA box （-29 - -22）, CAAT box （-193 - -189）, wound, and drought response elements. Expression vectors of Ell promoter gus fusion were constructed with the promoters of 1 200 and 2 000 bp regions, respectively. Transgenic tomato plants were obtained through Agrobacteriummediated transformation. Histochemical analysis of GUS activity in various tissues showed that the two promoters were able to direct fruit-specific gene expression. The expression driven by promoter of 2 000 bp upstream fragment could increase GUS activity with the maturation of tomato fruits. The promoter of -1 200 bp fragment could direct gus gene expression in fruits with the inductions of drought and wounding. The regulatory region for fruit-specificity was probably located in the region of 1 200 bp of 5′-flanking sequence and some positive regulatory elements or enhancers may exist in the region from -1 200 to -2000 bp.
