版纳植物园发现基因JcFT能够促进小桐子开花

摘要 : 中国科学院西双版纳热带植物园热带植物资源可持续利用重点实验室的能源植物分子育种研究组表明，JcFT是小桐子的成花素基因，能够促进植物开花。该研究结果有助于阐明小桐子的开花分子机理，从而为小桐子的遗传改良以及转基因育种奠定基础。相关文章发表于2014年5月8日的《BMC Plant Biology》杂志上。

植物的FT/TFL1基因家族属于磷脂酰乙醇胺结合蛋白 (phosphatidyle ethanolamine binding protein，PEBP) 基因家族，含有单一且非常保守的PEBP结构域。FT/TFL1基因家族广泛地存在于裸子植物和被子植物中。根据其结构和功能, FT/TFL1基因家族分为FT (FLOWERING LOCUS T) 类、TFL1 (TERMINAL FLOWER 1) 类和MFT (MOTHER OF FT AND TFL1) 类3个亚家族。其中，FT基因是成花素基因，在植物的成花转变过程中起着重要作用，具有促进植物开花的功能。

中国科学院西双版纳热带植物园热带植物资源可持续利用重点实验室的能源植物分子育种研究组博士研究生李超琼与其合作者一起在导师徐增富研究员的指导下，对能源植物小桐子 (Jatropha curcas) 的FT同源基因JcFT进行了克隆分析。通过蛋白序列和进化树分析，发现JcFT蛋白含有FT类蛋白所具有的保守氨基酸位点和结构域，而且与多年生木本植物如荔枝、杨树等的FT蛋白具有较高的同源性。

分析发现，JcFT主要在小桐子的生殖器官中表达。使用组成型表达的花椰菜花叶病毒35S (CaMV 35S) 启动子和韧皮部特异性表达的拟南芥蔗糖转运蛋白2 (AtSUC2) 启动子超量表达JcFT的转基因小桐子和拟南芥均表现出极度早花的现象。同时，在超量表达JcFT转基因植株中FT下游的开花相关基因的表达明显上调。

该研究结果表明，JcFT是小桐子的成花素基因，能够促进植物开花。该研究结果有助于阐明小桐子的开花分子机理，从而为小桐子的遗传改良以及转基因育种奠定基础。

相关研究结果发表于国际专业期刊BMC Plant biology上。

原文摘要：

Isolation and functional characterization of JcFT, a FLOWERING LOCUS T (FT) homologous gene from the biofuel plant Jatropha curcas

Chaoqiong Li, Li Luo, Qiantang Fu, Longjian Niu and Zeng-Fu Xu

Background

Physic nut (Jatropha curcas L.) is a potential feedstock for biofuel production because Jatropha oil is highly suitable for the production of the biodiesel and bio-jet fuels. However, Jatropha exhibits low seed yield as a result of unreliable and poor flowering. FLOWERING LOCUS T (FT) -like genes are important flowering regulators in higher plants. To date, the flowering genes in Jatropha have not yet been identified or characterized.

Results

To better understand the genetic control of flowering in Jatropha, an FT homolog was isolated from Jatropha and designated as JcFT. Sequence analysis and phylogenetic relationship of JcFT revealed a high sequence similarity with the FT genes of Litchi chinensis, Populus nigra and other perennial plants. JcFT was expressed in all tissues of adult plants except young leaves, with the highest expression level in female flowers. Overexpression of JcFT in Arabidopsis and Jatropha using the constitutive promoter cauliflower mosaic virus 35S or the phloem-specific promoter Arabidopsis SUCROSE TRANSPORTER 2 promoter resulted in an extremely early flowering phenotype. Furthermore, several flowering genes downstream of JcFT were up-regulated in the JcFT-overexpression transgenic plant lines.

Conclusions

JcFT may encode a florigen that acts as a key regulator in flowering pathway. This study is the first to functionally characterize a flowering gene, namely, JcFT, in the biofuel plant Jatropha.

作者：中科院

;