异源表达拟南芥赤霉素2–氧化酶基因对矮牵牛形态发育的影响

Impact of Heterologous Expression of a Gibberellin 2-oxidase Gene from Arabidopsis on Morphology Development in Transgenic Petunia

拟南芥赤霉素2–氧化酶基因AtGA2ox1在矮牵牛(Petunia hybrida)中过量表达导致转基因植株开花延迟,株形明显矮化,花冠变小,花冠表皮细胞变小,但花色变化不明显。施用多效唑对矮牵牛花冠的影响与过量表达AtGA2ox1一致。用拟南芥茎特异性表达基因At3g56700的启动子驱动AtGA2ox1在矮牵牛中表达时,转基因植株的表型变化在株系间存在明显的差异,但外源基因在茎中的表达量都明显高于叶和花中的,果实和种子的发育未受影响,通过对转基因后代的筛选可以获得株形矮化,其它性状的发育受影响较小的转基因株系。

Overexpression of Arabidopsis gibberellin 2-oxidase gene AtGA2ox1 led to the delay of flowering in petunia. The transgenic plants were obviously dwarfed and the size of transgenic flower and the adaxial petal epidermal cells were reduced. However,the flower color of transgenic plants was not altered. The usage of paclobutrazol on flower buds had similar effects on petunia flowers as the overexpression of AtGA2ox1 in petunia plants. For the purpose of bypassing the unwanted effects raised by overexpression of AtGA2ox1,a 2.1 kb 5′ upstream promoter sequnce of the stem specific gene At3g56700 from Arabidopsis was used to drive the expression of AtGA2ox1 in petunia. The transgenic plants showed dwarf phenotype and other morphologic changes in various degrees. However AtGA2ox1 gene accumulated at higher levels in stems than in leaves and flowers and the expression of heterologous AtGA2ox1 did not hazard the development of fruits and seeds in these transgenic plants. Campact transgenic plants without obviously detrimental alternations could be found from the offspring of transgenic plants expressing AtGA2ox1 drived by the promoter of At3g56700.