Physic nut (Jatropha curcas L.) has been propagated as a unique and potential biodiesel plant owing to its multipurpose value, high oil content, adaptability to marginal lands in a variety of agro-climatic conditions, noncompetitiveness with food production, and high biomass productivity. The FLOWERING LOCUS T (FT) gene plays a crucial role in the transition from vegetative growth to flowering, which is a potent factor integrating the flowering signals. To date, the flowering genes in Jatropha have not yet been identified or characterized.
Prof. XU Zengfu of Xishuangbanna Tropical Botanical Garden (XTBG) and his students cloned and characterized the Jatropha FT homolog and designated as JcFT. They also analyzed the function of JcFT in floral induction using transgenic Arabidopsis and Jatropha.
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.
The study found that JcFT was mainly expressed in the reproductive organs, including female flowers, fruits, and seeds. JcFT also induced early flowering in transgenic Arabidopsis and Jatropha, indicating that JcFT acted as a flowering promoter in Jatropha.
