Different Roles of Flowering-Time Genes in the Activation of Floral Initiation Genes in Arabidopsis

Abstract

We have analyzed double mutants that combine late-flowering mutations at four flowering-time loci (FVE, FPA, FWA, and FT) with mutations at the LEAFY (LFY), APETALA1 (AP1), and TERMINAL FLOWER1 (TFL1) loci involved in the floral initiation process (FLIP). Double mutants between ft-1 or fwa-1 and lfy-6 completely lack flowerlike structures, indicating that both FWA and FT act redundantly with LFY to control AP1. Moreover, the phenotypes of ft-1 ap1-1 and fwa-1 ap1-1 double mutants are reminiscent of the phenotype of ap1-1 cal-1 double mutants, suggesting that FWA and FT could also be involved in the control of other FLIP genes. Such extreme phenotypes were not observed in double mutants between fve-2 or fpa-1 and lfy-6 ap1-1. Each of these showed a phenotype similar to that of ap1-1 or lfy-6 mutants grown under noninductive photoperiods, suggesting a redundant interaction with FLIP genes. Finally, the phenotype of double mutants combining the late-flowering mutations with tfl1-2 were also consistent with the different roles of flowering-time genes.

GENEVESTIGATOR. Arabidopsis Microarray Database and Analysis Toolbox

“…3, H and I), but lower levels in all other stages. In contrast, two genes involved in flowering (APETALA1 [At1g69120, Pelaz et al, 2001] and FLOWERING LOCUS T [At1g65480, Ruiz-Garcia et al, 1997]) were shown to be most abundantly expressed in the flowering stages (Fig. 3, J and K).…”

Flowering in time: genes controlling photoperiodic flowering inArabidopsis

“…Good evidence for the role of the plant circadian clock in £owering has come with the isolation of Arabidopsis mutants with both altered circadian rhythms and £owering time and with the identi¢cation of circadianregulated £owering time genes (for reviews, see Millar 1999;Somers 1999;Samach & Coupland 2000;McClung 2000).…”

“…PHYA may exert its e¡ect on photoperiodic £owering by having a direct e¡ect on the expression or activity of £owering-time genes (Samach & Coupland 2000), but this needs to be tested. Alternatively, PHYA may also in£uence photoperiodic £owering by resetting the circadian clock, because high intensity far red given at the end of the night period rephased the rhythm of leaf movement in wild-type Arabidopsis but not in phya mutants (Yanovsky et al 2000).…”

The tomato FT ortholog triggers systemic signals that regulate growth and flowering and substitute for diverse environmental stimuli

“…FT is a major integrator of the genetic pathways to flowering in short and long days (4,5); it encodes a signaling factor (6, 7) and is not expressed in the SAM proper (8) but can be detected, upon induction, in shoot apices (SAPs) containing young leaves (9). Flowering is delayed in mutant ft plants (10,11), and when FT is overexpressed, flowering occurs earlier with a determinate inflorescence (12,13). FT is regulated by the flowering-time gene CONSTANS in both long-and short-day plants (14,15), and grafting experiments in Arabidopsis have shown that systemic induction of flowering by CONSTANS is most likely mediated by FT (16,17).…”