High impact information on FT

• PFT1 functions downstream of phyB to regulate the expression of FLOWERING LOCUS T (FT), providing evidence for the existence of a light-quality pathway that regulates flowering time in plants [1].
• Expression of the rice orthologue of the Arabidopsis CONSTANS (CO) gene was increased in the transgenic rice, whereas expression of the rice orthologue of FLOWERING LOCUS T (FT) was suppressed [2].
• CO is a transcriptional activator that accelerates flowering time in long days, at least in part by inducing the expression of FLOWERING LOCUS T (FT) [3].
• Three mutations that affect circadian rhythms and flowering time alter CO and FT expression in ways that are consistent with their effects on flowering [4].
• The SOC1 and FT genes are also regulated by a second flowering-time pathway that acts independently of CO [5].

Biological context of FT

• Therefore, GI plays a general role in controlling circadian rhythms, and this is different from its effect on the amplitude of expression of CO and FT [6].
• We propose that FT functions through partner-dependent transcriptional activation of these and as-yet-unknown genes and that this occurs at several sites [7].
• We found that ft-10 almost completely suppressed the early flowering phenotype of CO overexpressor plants, whereas soc1-2 partially suppressed the phenotype, suggesting that FT is the major output of CO [8].
• The tree structure suggests that the ancestral grass genome had at least two MFT-like genes, two TFL1-like genes, and eight FT-like genes [9].
• These results suggest that PIF3 may play an important role in the control of flowering through clock-independent regulation of CO and FT gene expression in Arabidopsis [10].

Anatomical context of FT

• For photoperiodism light, acting through phytochromes and cryptochromes, the main photomorphogenetic photoreceptors, acts to entrain and interact with a circadian rhythm of CONSTANS (CO) expression leading to transcription of the mobile floral integrator, FLOWERING LOCUS T (FT) [11].

Associations of FT with chemical compounds

• Two of these genes, SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) and FLOWERING LOCUS T (FT), are required for CO to promote flowering; the others are involved in proline or ethylene biosynthesis [5].

Regulatory relationships of FT

• These experiments demonstrated that GI acts between the circadian oscillator and CO to promote flowering by increasing CO and FT mRNA abundance [6].
• CONSTANS activates SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 through FLOWERING LOCUS T to promote flowering in Arabidopsis [8].
• Phytochrome B in the mesophyll delays flowering by suppressing FLOWERING LOCUS T expression in Arabidopsis vascular bundles [12].
• Arabidopsis TERMINAL FLOWER 2 gene encodes a heterochromatin protein 1 homolog and represses both FLOWERING LOCUS T to regulate flowering time and several floral homeotic genes [13].

Other interactions of FT

• Like LFY, FT acts partially downstream of CONSTANS (CO), which promotes flowering in response to long days [14].
• FLOWERING LOCUS T (FT), which acts in parallel with the meristem-identity gene LEAFY (LFY) to induce flowering of Arabidopsis, was isolated by activation tagging [14].
• Although <60% identical, we have shown that swapping a single amino acid is sufficient to convert TFL1 to FT function and vice versa [15].
• Loss of GI function causes late flowering and reduces CO and FT RNA levels [16].
• Taken together, these data suggest that CO activates SOC1 through FT to promote flowering in Arabidopsis [8].

Analytical, diagnostic and therapeutic context of FT

• Our RT-PCR data indicate that phytochrome signals repress mRNA expression of FT orthologs, whereas SE1 can function to promote and suppress mRNA expression of the FT orthologs under SD and LD, respectively [17].

References