Antisense ACC Synthase Transgene Regulating The Growth And Development Of Torenia Fournieri

Despite its simple two-carbon structure, ethylene is a potent modulator of plant growth and development. Ethylene is involved in many aspects of the plant life cycle that from seed germination to fruit ripening. Because ethylene is tightly relative to flower senescence and fruit ripening, it is very important in business to inhibite ethylene biosynthesis to delay senescence. ACC synthase is the rate-limiting enzyme of ethylene biosynthesis, and the rate of ethylene biosynthesis is tightly controlled by the activeness of ACC synthase in plants. Reseaches have been made on inhibition of ethylene biosynthesis with antisense RNA, and that suggest that flower senescence can be delayed by inhibition of ethylene biosynthesis with antisense RNA .Torenia fournier , an ornamental plant, has a special embryo sac development model. It has a naked embryo sac that protrudes from the micropyle into the cavity between the funiculus and placenta. As embryo sac is mature, the egg cell, the two synergids and about half the central cell are located outside the micropyle. Therefore, Torenia fournieri is a very suitable model plant for studies of double fertilization in living material. In the experiment, we have explored optimal conditions for the transformation of Torenia Fournier, and transformated it with antisense ACC synthase gene to get transformated Torenia Fournier plants with flower longevity extension andmore tolerance to abiotic stress.Our experiment indicates: (1) The optimal concentration of kanamycin for screening Torenia Fournier regenerated buds was 400 mg/L.The ideal transformation was obtained in the following conditions: The leaf discs were dipped in Agrobacterium suspension that OD600 was 0.1 for 10~ 20 min; subsequently cocultivated on the MS solid coculture medium containing 20umol/L acetosyringon for 7 to 8 d at 23℃, and the induction ratio of regenerated buds was 27.2%. 16h light/8h dark photoperiod was the ideal cocultivation photoperiod. The stem sections were better receptors for Torenia Fournier transformation. Transformed plants of Torenia fournieri were obtained under above conditions and the ratio of transformation was 24.1 %. The transformant would flower in 8 to 10 weeks, sometimes under in vitro culture, after the leave dies was infected by Agrobacterium tumefaciens. The transformation system would be a valuable tool for flower development and double fertilization studies. (2) Compared with wild-type Torenia Fournier, antisense ACC synthase gene transformated plants of Torenia fournieri had the following changes: The rate of ethylene biosynthesis dramatically decreased in the plants. Cholrophyll content in the leaves is 1.15 times of that of the wild-type Torenia Fournier leaves. The transformed plants had more flowers. Flower longevity extension was one day. The number and weight of seeds in individual capsules of transformats also increased. Polyamines contents in the leaves increased and the transformants had more tolerance to abiotic stress including oxidative stress, acid stress, dehydration stress.