蕙兰Flowering locus T基因的克隆及其对开花的影响

Isolation of Flowering Locus T Ortholog and the Effects on Blooming of Cymbidium faberi

【目的】探讨CfFT基因在蕙兰成花中的作用。【方法】采用RT-PCR结合RACE技术从蕙兰(Cymbidiumfaberi)中克隆Flowering locus T(FT)同源基因CfFT。采用实时定量RT-PCR对不同组织及不同花发育时期CfFT进行表达分析。将该基因克隆到PBI121载体上导入烟草中,并对不同转基因烟草株系中的CfFT、NFL、NtFUL和NAP1基因进行实时定量RT-PCR分析。【结果】对蕙兰花芽分化不同时期的CfFT的表达分析表明,CfFT在花芽分化初期的表达量最高,之后随着花芽的成熟表达量逐渐降低。将CfFT导入烟草进行异源表达,转基因株系表现出明显的早花表型。对开花时间不一的转基因株系中的CfFT表达分析表明,其表达量与转基因烟草开花时间早晚成正比。进一步对这些株系内源的NFL、NAP1和NtFUL表达分析表明,NFL、NAP1和NtFUL基因的表达量与CfFT表达成正比,说明NFL、NAP1和NtFUL的表达受FT基因的上游调控。【结论】在烟草中异源表达蕙兰中的CfFT基因能促进烟草提前开花。

[Objective] The objective of this study was to analyze the function of Flowering locus T（FT） on blooming in Cymbidium faberi. [ Method ] The full-length cDNA sequence of CfFT was obtained by RT-PCR and RACE cloning technology. The expression patterns of CfFT in different tissues and flower buds of different developmental stages were analyzed by real-time quantitative RT-PCR. To investigate the function of CfFT, an expression vector was constructed for transformation into tobacco by using agrobacterium-mediated method. [ Result ] In flowers, CfFT was expressed more in young flower buds than in mature flowers and was predominantly expressed in young ovary. Ectopic expression of CfFT in transgenic tobacco plants showed novel phenotypes by flowering earlier than wild-type plants. Real-time quantitative RT-PCR analysis suggested that expression levels of CfFT closely related with the flowering time of different 35S：：CfFT transgenic tobacco lines. Further analysis of the flower time related genes indicated that the expression of genes LEAFY （LFY）, APETALLA1 （AP1）, FRUITFULL （FUL） and SEPALLATA1 （SEP1） were closely related with the expression of FT in 35S：：CfFT transgenic tobacco plants. [ Conclusion] Ectopic expression of CfFT gene promote flowering in transgenic tobacco.