Post-fertilization expression of FLOWERING LOCUS T suppresses reproductive reversion.

Liangyu Liu,Sonja Klemme,Sara Farrona,Franziska K Turck

doi:10.3389/fpls.2014.00164

Abstract

FLOWERING LOCUS T (FT) encodes a systemic signal communicating the perception of long day photoperiod from leaves to the shoot apex to induce the floral transition. Transient expression of FT in the phloem companion cells of rosette leaves for one to several days was previously shown to be sufficient to commit plants to flowering. Here we show that partial commitment results in pleiotropic inflorescence meristem reversion phenotypes. FT expression is much stronger in organs formed after the floral transition such as cauline leaves, sepals, and developing siliques. We show that expression of FT and its paralog TWIN SISTER OF FT (TSF) after the floral transition plays a role in inflorescence meristem stabilization even if plants flower very late in development. CONSTANS (CO), the major activator of FT, is not required to prevent late reproductive reversion. The requirement for FT is temporal since reproductive reversion to a vegetative state occurs only in recently formed inflorescence meristems. Unlike for the expression of FT in leaves, neither the distal putative FT enhancer nor long-day photoperiod is required for FT expression in developing siliques. Expression of FT in developing siliques and their supporting stems is sufficient to stabilize flowering during the sensitive developmental window indicating that fruit generated FT participates in inflorescence stabilization.

Highlights

In many plant species, FLOWERING LOCUS T (FT)-like genes play a critical role in the photoperiod dependent timing of the transition from the vegetative to the reproductive stage (Ballerini and Kramer, 2011)
extended short day (ESD) growth conditions provide 8 h of full light supplemented by 8 h of low intensity light sufficient to trigger long day (LD) light responses, such as FT induction, while minimizing the differences in growth rate observed between plants grown in short days (SD) and long days (LD) conditions
The severity of the phenotype was inversely correlated with the number of ESDs the plants had experienced (Figure 1E) indicating that maintained FT expression participates in preventing reversion of the inflorescence meristem to a more vegetative or arrested state

Summary

Introduction

FLOWERING LOCUS T (FT)-like genes play a critical role in the photoperiod dependent timing of the transition from the vegetative to the reproductive stage (Ballerini and Kramer, 2011). If days are longer than the critical day length, CO protein is stabilized by light and capable of promoting FT expression (Valverde et al, 2004). In biennial Arabidopsis plants, high levels of the transcription factor FLOWERING LOCUS C (FLC) prior vernalization prevent the activation of FT in long-day photoperiod (Hepworth et al, 2002; Michaels et al, 2005). The effect of FLC is partially dependent on the presence of SHORT VEGETATIVE PHASE (SVP), with which it may form a complex (Hartmann et al, 2000; Li et al, 2008). Plant age participates in FT regulation via the microRNA 156 (miR156) pathway (Mathieu et al, 2009)

Methods

Results

Conclusion