Functional Characterization of PhapLEAFY, a FLORICAULA/LEAFY Ortholog in Phalaenopsis aphrodite.
The plant-specific transcription factor LEAFY (LFY) is considered to be a master regulator of flower development in the model plant, Arabidopsis. This protein plays a dual role in plant growth, integrating signals from the floral inductive pathways and acting as a floral meristem identity gene by activating genes for floral organ development. Although LFY occupies an important position in flower development, the functional divergence of LFY homologs has been demonstrated in several plants including monocots and gymnosperms. In particular, the functional roles of LFY genes from orchid species such as Phalaenopsis that contain unique floral morphologies with distinct expression patterns of floral organ identity genes remain elusive. Here, PhapLFY, an ortholog of Arabidopsis LFY from Phalaenopsis aphrodite subsp. formosana, a Taiwanese native monopodial orchid, was isolated and characterized through analyses of expression and protein activity. PhapLFY transcripts accumulated in the floral primordia of developing inflorescences, and the PhapLFY protein had transcriptional autoactivation activity forming as a homodimer. Furthermore, PhapLFY rescues the aberrant floral phenotypes of Arabidopsis lfy mutants. Overexpression of PhapLFY alone or together with PhapFT1, a P. aphrodite subsp. formosana homolog of Arabidopsis FLOWERING LOCUS T (FT) in rice, caused precocious heading. Consistently, a higher Chl content in the sepals and morphological changes in epidermal cells were observed in the floral organs of PhapLFY knock-down orchids generated by virus-induced gene silencing. Taken together, these results suggest that PhapLFY is functionally distinct from RICE FLORICAULA/LEAFY (RFL) but similar to Arabidopsis LFY based on phenotypes of our transgenic Arabidopsis and rice plants.
Biotechnology Center in Southern Taiwan (BCST), No. 59, Siraya Blvd, Xinshi Dist., Tainan 74145/Agricultural Biotechnology Research Center, Academia Sinica, No. 128, Sec. 2, Academia Road, Nankang, Taipei 11529, Taiwan Institute of Tropical Plant Science, National Cheng Kung University, No. 1 University Road, East Dist., Tainan 70101, Taiwan florigen@gate.sinica.edu.tw.
Seonghoe
S
Jang
D017360:Arabidopsis / Q000235:genetics; D003001:Cloning, Molecular; D035264:Flowers / Q000378:metabolism; D015870:Gene Expression; D009154:Mutation; D029595:Orchidaceae / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D010940:Plant Proteins; D014157:Transcription Factors
Flower development; Flowering; LEAFY; Phalaenopsis aphrodite; Rice