Molecular characterization and functional analysis of a Flowering locus T homolog gene from a Phalaenopsis orchid

Warm day and cool night conditions significantly induce reproductive spike formation in Phalaenopsis plants; hence, determining the flowering mechanism regulating the reproductive transition is important. Flowering locus T (FT) plays important roles in flowering induction in several plants. To explore spike induction by warm days and cool nights in Phalaenopsis orchids, we isolated the FT (PhFT) from Phalaenopsis hybrid Fortune Saltzman. The cDNA of PhFT was 809- bp long and contained a 531-bp open reading frame encoding a putative protein of 176 amino acids, a 58-bp 5'-untranslated region (UTR), and a 220-bp 3'-UTR. The predicted molecular mass of PhFT was 19.80 kDa, with an isoelectric point of 8.68. The PhFT was predicted to possess the conserved functional regions of the phosphatidylethanolamine-binding protein superfamily. Nucleotide sequence data indicated that PhFT contained 3 introns and 4 exons. Sequence alignment and phylogenetic analyses of PhFT revealed high homology to the FT proteins of Cymbidium goeringii and Oncidium Gower Ramsey. Quantitative real- time polymerase chain reaction analysis indicated that PhFT mRNA