Characterization and expression analysis of PhalLFY, a homologue in Phalaenopsis of FLORICAULA/LEAFY genes

FLORICAULA/LEAFY (FLO/LFY) homologues are floral meristem identifying genes and play a key role in flower development among diverse species. Phalaenopsis is one of the world's most popular flowers. To understand the molecular mechanism of the reproduction process, PhalLFY, a FLO/LFY homologue gene was cloned from Phalaenopsis hybrida (cv.wedding promenade) and its expression pattern was analysed during vegetative as well as reproductive development. The full cDNA of PhalLFY was 1655 bp in length with an open reading frame (ORF) of 1422 bp encoding 424 amino acids. The analysis based on amino acid sequence alignment showed that PhalLFY shared a high degree of similarity to LFY-like (68%) from Anacamptis, LFY-like (61%) from Hyacinthus, RFL (60%) from Oryza sativa and LFY (54%) from Arabidopsis. A transient expression assay using PhalLFY/GFP fusion protein showed that PhalLFY was nucleus-localized protein. Semi-quantitative RT-PCR analysis and in situ hybridization results showed that PhalLFY was expressed both in the vegetative organs as well as the reproductive organs. Its transcripts accumulated at higher levels in the stem during the transition from vegetative to reproductive growth, especially in the inflorescence meristems, floral meristems, floral primordia and all floral organs during the floral developmental stage of P. hybrida. Moreover, PhalLFY transcript was lower in the young phase than in the mature phase. These results suggest that PhalLFY is a FLO/LFY homologue probably involved in the control of Phalaenopsis reproductive development.