CaMV35S启动子驱动的FT基因调控杨树早期开花的初步研究

为了研究CaMV35S启动子驱动的FT基因对转基因杨树Populus早期开花的影响,利用Gateway技术构建了35S::FT基因表达载体,并对杨树进行了遗传转化,从转基因杨树花的发育、花器官变异等方面初步探讨了35S::FT促进杨树早期开花性能。结果表明:35S::FT转基因杨树分生组织属性的改变及初始花结构的形成发生于试管培养阶段;花开始发育后如不及时把开花植株继代培养或转至土壤温室培养,初始花结构会凋谢枯萎,不能继续发育。转基因植株花器官的分化与发育发生于温室培养阶段的3~5周内,能够分化出典型的花器官,但发育不完全,具雌雄蕊、花盘结构,无成熟苞片结构,雄蕊不能成熟发育。35S::FT诱导的花均为单朵花,而非野生型的柔荑花序;多数花属于单性花,但转基因雄性无性系中会出现两性花。转基因植株的开花率随着试管苗继代次数的增加而急剧下降,但两性花比例会上升。

FT gene with a CaMV35S promoter to control early flowering of transgenic poplar

To study the effects on the early flowering capacity of the FLOWERING LOCUS T（FT） gene in transgenic poplar driven by a Cauliflower Mosaic Virus 35S （CaMV35S） promoter, provide basic data for effective application of FT gene on forest trees, an FT gene vector driven by a CaMV35S promoter was constructed using Gateway technology, and then genetic transformation of hybrid poplar was performed with this vector. The early flowering capability of transgenic poplar induced by 35S::FT was discussed both from flower development and floral organ variation viewpoints. Results showed that transformation of the meristem attributive and initial floral structure of 35S::FT transgenic poplar happened in the tube culture stage. If the flowering plants were not sub-cultured in vitro or timely transplanted into soil to culture in a greenhouse, the initial floral structure withered or ceased development. Within 3-5 weeks of greenhouse culture the initial floral structure continued to develop and finished floral organ differentiation and development. The floral organ was incomplete typically with pistil/stamen and flower disc structures but no mature bract structures; stamens also failed to mature. Flowers induced by 35S::FT were single flowers rather than catkins as with wild-types. Most flowers were unisexual, but bisexual flowers appeared on male transgenic plants. Flowering frequency of transgenic plants declined sharply with the increase of subculture time, but the proportion of bisexual flowers on male transgenic plants rose. 35S promoter is not suitable in genetic transformation for the purpose of getting normal floral organ.［Ch, 1 fig. 1 tab. 22 ref.］