| Abstract: | 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 1 200 base pair (bp) candidate fragment was amplified from the cucumber genome with degenerated primers derived from the ACO amino acid consensus sequence among different plant species. The coding region and its upstream (1 155 bp) were obtained by vector-mediated inverse PCR. The novel 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 the new gene (CsACO4, GenBank accession number AY450356) was in accordance with the evolution relationship of genetics among various plant species. Northern blotting showed that the gene expressed among female flowers of gynoecious and monoecious genotypes, it could not express in other organs. This implied that the gene might be correlated with the female behavior positively. Further work is on the way to demonstrate the complexity of the relationship between the endogenous ethylene and the sex determination. |
