Kobayashi等(Kobayashi et al., 1999)采用活化标签的方法首次在拟南芥早花突变体中分离到FLOWERING LOCUS T (FT)基因，其编码的氨基酸序列与TFL1(TERMINAL FLOWER 1)基因编码的氨基酸序列相似性大于50%，根据其编码的氨基酸序列预测其蛋白与TFL1蛋白同属于拟南芥的一个小基因家族，称为FT/TFL1基因家族。已有研究表明，FT基因可以整合不同花发育途径如光周期途径、自主途径和春化途径的信号从而促进植物开花(Michaels and Amasino, 1999; Corbesier and Coupland, 2006)。FT基因除受花期基因CONSTANS(CO)调节促进开花以外，在拟南芥中最新发现的温度感知途径和光质途径也是通过调节FT的表达而进行开花时间调节(Blazquez et al., 2003; Cerdan and Chory, 2003)。

目前发现拟南芥基因组包含6个FT/TFL1基因家族成员，它们分别是：TFL1、FT、BFT (BROTHER OF FT AND TFL 1)、MFT (MOTHER OF FT AND TFL 1)、TFT (TWIN SISTER OF FT)和ATC (Arabidopsis thaliana CEN TRORADIALIS homologue) (Searle and Coupland, 2004)。至今为止，研究者已经在苹果(Kotoda and Wada, 2005; Kotoda et al., 2010)、大麦(Karsai et al., 2008)、红叶黎(Chab et al., 2008)、油菜(Wang et al., 2009)、白芥(Aloia et al., 2009)、毛环竹(Hisamoto et al., 2008)、美洲黑杨(Igasaki et al., 2008)、温州蜜柑(Kobayashi et al., 1999)、西葫芦(Lin et al., 2007)、南瓜(Lin et al., 2007)等物种中分离到了拟南芥FT同源基因。现有的研究表明，FT蛋白起成花素的作用(Corbesier et al., 2007; Lin et al., 2007; Tamaki et al., 2007)，FT蛋白运送到顶端分生组织后，会激活FLOWERING LOCUS D(FD)的表达，随后FT蛋白和FD蛋白组成蛋白复合物共同激活APETALA1(AP1)、LEAFY(LFY)等基因的表达，从而促进拟南芥开花(Abe et al., 2005)。

菊科是被子植物中最大的科，也是双子叶植物中进化程度最高的科。甘菊为菊科菊属中的二倍体植物，我们利用PCR、RT-PCR及PCR-RACE技术从甘菊中分离到1个拟南芥FT同源基因，命名为ClFT。ClFT基 因的GenBank登录号为GU120195，其cDNA全长为837 bp，编码174个氨基酸和一个终止密码子，其推测的氨基酸序列中包含第70位~第74位氨基酸残基间的D-P-D-x-P模块、第86位的His残基和 第116位~第119位氨基酸残基间的G-x-H-R模块，这些保守序列均与配体结合位点的形成有关。同源序列比对分析表明，该推测氨基酸与其它物种同源 性在60%以上，与旁系同源基因在不同物种中的物种演变的进化顺序相同。这些结果将为研究菊科植物花发育的分子机理以及利用转基因技术调控观赏植物花期提 供新的基因资源。

作者贡献
王琳琳是本研究的实验设计和实验研究的执行人，付建新完成论文初稿的写作，戴思兰教授是项目的构思者及负责人，指导实验设计，数据分析，论文写作与修改。全体作者都阅读并同意最终的文本。

致谢
本研究由高等学校博士学科点专项科研基金(20070022009)、国家自然科学基金项目(30871726)和国家863计划项目(2006AA100109)项目资助，作者感谢两位匿名的同行评审人的评审建议和修改建议。

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