Isolation and functional analysis of FLOWERING LOCUS T orthologous gene from Vanda hybrid

Vanda is an important ornamental tropical orchid in Thailand and shows great potential in international markets. Since there has been limited research on flowering processes and regulations, flower production programs cannot be properly managed. To understand the genetic mechanisms in the Vanda flowering process, the ortholog of the FLOWERING LOCUS T (FT) gene (VaFT) was isolated and characterized by using Vanda ‘Ratchaburi-Fusch Katsura’. An open reading frame of 531 bp, translating a protein of 176 amino acids (AAs), was obtained from VaFT. The AA sequence alignment of VaFT indicated that it contains a conserved domain, distinctive to the phosphatidylethanolamine-binding proteins (PEBPs) superfamily, and shares high homology with other orchid FT proteins: 93% of PaFT from Phalaenopsis aphrodite, 91% of CgFT from Cymbidium goeringii and 89% of OnFT from Oncidium Gower Ramsey. Ectopic expression of VaFT in transgenic Arabidopsis resulted in activation of floral meristem identity gene APETALA1 (AP1) and early flowering with fewer rosette leaves than non-transgenic Arabidopsis. Our data suggests that VaFT is apparently a PEBPs gene in orchids that conducts the transition of flowering.