Abstract
In Arabidopsis, several genetic pathways controlling the floral transition (flowering) are integrated at the transcriptional regulation of FT, LFY, and SOC1. TSF is the closest homolog of FT in Arabidopsis. TSF expression was regulated by CO and showed diurnal oscillation. tsf mutation enhanced the phenotype of ft in both LD and SD conditions. TSF and FT also shared similar modes of regulation by FLC, an integrator of autonomous and vernalization pathways. Consistently, TSF over-expression caused a precocious-flowering phenotype independent of photoperiods or CO, or FLC. These observations suggest that TSF is a new member of the floral pathway integrators and promotes flowering largely redundantly with FT. Interestingly, expression patterns of TSF and FT in seedlings did not overlap, although both were expressed in the phloem. This finding indicates that the phloem is the site where multiple regulatory pathways are integrated at the transcriptional regulation of FT and TSF.
