Abstract: Flowering Locus T (FT) gene and its homologues play an important role in promotion flowering plants and changes in developmental stage. The full cDNA of FT gene was isolated from Betula platyphylla Suk. by methods of reverse transcription polymerase chain reaction (RT-PCR) and 5′ and 3′ rapid amplification of cDNA ends (RACE). Results showed that FT gene contains an open reading frame (ORF) of 525 bp encoding 174 amino acids. Molecular weight of the deduced protein of BplFT is 19.6 kDa and the theoretical isoelectric point is 7.73. The FT conserved protein domain of PEBP was confirmed in the sequence, so the isolated gene was named as BplFT, and registered in GenBank with accession number JQ409561. The deduced amino acid sequence shared 74%-93% of identity with other sixteen plant species, the maximum identity was with Ficus carica(93%) and minimum identity with Arabidopsis thaliana(74%). A phylogenetic tree was constructed according to multiple sequences alignment of all the seventeen plant species. Transcription expression of BplFT was analyzed by qRT-PCR in different tissues and periods in B.platyphylla. Results showed that BplFT was more highly expressed in vegetative organs than in floral organs, expression quantity was higher in mature tissues than in young tissues, the highest expression is in mature stem. It inferred that BplFT gene play an important role in mature tissues development and transfactor may involved in the formation of secondary cell wall in Betula. In addition, a natural male inflorescence-abnormal mutant of B.platyphylla was used for transcription analysis of BplFT. Results showed that BplFT gene is expressed up-regulatedly in female inflorescences, male inflorescences, young leaves and young shoots, which predicted that BplFT should not only be involved in the development of vegetative tissues, but also play some roles in the development of floral organs.

Key words: Betula platyphylla, FT, transcription expression, qRT-PCR, flower development, mutant