Cloning And Functional Analysis Of FT Gene Family From Populus Simonii

FT(FLOWERING LOCUS T) gene is an inducible factor in the plant in blossom. FT not only plays a key role in photoperiod pathway, but also regulates flowering development as an intergrated gene which intregrates the signals in different flower developmental pathways.We cloned three genes from Populus simonii in this study, PsFT3, PsFT4, PsFT5, and constructed plant expression vectors for genetic transformation to verify their functions. The main conclusions of this study were as following:1. We totally cloned three Populus simonii FT genes by using homologous cloning method. The open reading frames of these three genes are 525 bp, which encoding a 174 amino acid residue protein which contian a typical PEBP domain. The result of sequence analysis showed that the similarity of protein sequence between them is up to 97.1%, and only had five different residues. Furthermore, we chose 11 plants’ amino acid sequences to analysis of genetic evolution. The result showed that the FT gene had very high similarity in those plants. PsFT had a closest relationship with Populus trichocarpa and Populus deltoids, then a closer genetic relationship with the Populus tomentosa, Fagus crenata, Camellia sinensis and so on. The phylogenetic relationship of Dimocarpus longan, Litchi chinensis, Citrus unshiu and other plants was relativly distant.2. The three PsFT genes were respectively cloned into the plant over expression vector pBI121 and virus vector TRV by Gateway technology.3. The three PsFT genes were transferred into tobacco mediated with Agrobacterium GV3101. All transgenic tobacco had early-flowering phenotype. Through real-time PCR result showed that the target genes were transcripted on a very high level in the transgenic tobacco plants.4. Furthermore, PsFT3, PsFT4, PsFT5 genes were transformed into Arabidopsis thaliana and hybrid poplar(P.davidiana×P.bollena) by Agrobacterium GV3101. By kanamycin selection of three genes we got the transgenic plants. The results of molecular biology detection showed that the target genes had already transfered into the Arabidopsis thaliana and hybrid poplar(P.davidiana×P.bollena). And we observed that all transgenic plants had early-flowering phenotype. To reveal the expression pattern of the downstream genes of FT, three flowering-related genes, AP1, SOC1 and LFY, were selected for real-time PCR analysis. The results showed that three downstream genes were upregulated due to the over-expression of FT and then induce the transgenic plant flower much earlier than control plant.