Over-expression of 1-aminocyclopropane-1-carboxylic acid oxidase Genes(ACO) from Vitis vinifera in Tomato(Solanum locopersicum) and Its Effects on Ethylene Release Rates
Abstract：Ethylene is an important plant endogenous hormone which controls fruit ripening and senescence, and 1-aminocyclopropane-1-carboxylic acid oxidase(ACO) is one of the key rate-determining enzymes in the biosynthesis of ethylene. VvACOs is coded by a small gene family, and the highest expression of VvACO1 and VvACO2, which are key genes regulating ethylene production changes during berry fruit development, is observed in the stage of veraison. In order to verify the influences of over-expression of VvACOs on ethylene release rates in tomato(Solanum locopersicum), Grapevine 1-aminocyclopropane-1-carboxylic acid oxidase (VvACO) genes were introduced into tomato genome by Agrobacturium mediated transformation method. The transgenic tomato plants were further verified with PCR and RT-PCR analysis, and ACO enzyme activities and ethylene release rates in the leaves of transgenic tomato plants were measured by gas chromatography. RT-PCR analysis indicated that three, four and six transgenic tomato lines with over-expressing VvACO1, VvACO2 and VvACO3 were obtained, respectively. The ACO enzyme activities and ethylene release rates in the transgenic plants were higher than those in non-transgenic tomato leaves and fruits. The highest ACO enzyme activities and ethylene release rates in the leaves and fruits of tomato transgenic lines with over-expressing VvACO1 and VvACO3 were observed, respectively. The transgenic tomato plants which over-expressing both VvACO1 and VvACO3 were normal morphological growth. The lowest ACO enzyme activities and ethylene release rates were observed in the tomato transgenic lines with over-expressing VvACO2, and the VvACO2 over-expressing plants were shown dwarf phenotype. Transgenic tomatoes that over-expressed of the each of the VvACO genes were analyzed for their growth physiological indexs, ethylene release rates, and ACO enzyme activies. Based on these results, functions of VvACO genes were preliminarily predicted.
