Functional Characterization of Phalaenopsis aphrodite Flowering Genes PaFT1 and PaFD

Abstract

We show that the key flowering regulators encoded by Phalaenopsis aphrodite FLOWERING LOCUS T1 (PaFT1) and PaFD share high sequence homologies to these from long-day flowering Arabidopsis and short-day flowering rice. Interestingly, PaFT1 is specifically up-regulated during flowering inductive cooling treatment but is not subjected to control by photoperiod in P. aphrodite. Phloem or shoot apex-specific expression of PaFT1 restores the late flowering of Arabidopsis ft mutants. Moreover, PaFT1 can suppress the delayed flowering caused by SHORT VEGATATIVE PHASE (SVP) overexpression as well as an active FRIGIDA (FRI) allele, indicating the functional conservation of flowering regulatory circuit in different plant species. PaFT1 promoter:GUS in Arabidopsis showed similar staining pattern to that of Arabidopsis FT in the leaves and guard cells but different in the shoot apex. A genomic clone or heat shock-inducible expression of PaFT1 is sufficient to the partial complementation of the ft mutants. Remarkably, ectopic PaFT1 expression also triggers precocious heading in rice. To further demonstrate the functional conservation of the flowering regulators, we show that PaFD, a bZIP transcription factor involved in flowering promotion, interacts with PaFT1, and PaFD partially complemented Arabidopsis fd mutants. Transgenic rice expressing PaFD also flowered early with increased expression of rice homologues of APETALA1 (AP1). Consistently, PaFT1 knock-down Phalaenopsis plants generated by virus-induced gene silencing exhibit delayed spiking. These studies suggest functional conservation of FT and FD genes, which may have evolved and integrated into distinct regulatory circuits in monopodial orchids, Arabidopsis and rice that promote flowering under their own inductive conditions.

Antagonistic Transcription Factor Complexes Modulate the Floral Transition in Rice

“…Mutants in which all four genes are silenced develop inflorescence stems where flowers are replaced by vegetative shoots (Kobayashi et al, 2012). This general mode of action of the florigens at the SAM has been observed in several plant species (Jang et al, 2015;Jaudal et al, 2015;Li and Dubcovsky, 2008). However, FACs can be deployed also in tissues different from the SAM to control a broad spectrum of developmental processes different from inflorescence formation.…”

Early Detection of the Orchid Flowering Gene PaFT1 in Tobacco Cells Using a GFP Reporter

“…The main gene on pGAS101 plasmid is PaFT1. PaFT1 gene is one of FT homologous genes isolated from P. aphrodite (Jang et al 2015). Analogous to Arabidopsis as the model plant, over expression of the PaFT1 gene is expected to accelerate flowering in plants.…”

De novo transcriptome sequencing and comparative analysis to discover genes related to floral development in Cymbidium faberi Rolfe

“…The FLOWERING LOCUS T ( FT ) gene activates the expression of a number of flower developmental genes (Mouradov et al 2002). In the orchid plant Phalaenopsis aphrodite , PaFT1 can suppress the delayed flowering caused by SHORT VEGATATIVE PHASE ( SVP ) and FRIGIDA ( FRI ) (Jang et al 2015). The Cymbidium FT orthologous gene was also cloned and ectopic expression of CgFT resulted in early flowering in transgenic Arabidopsi s (Huang et al 2012).…”