Abstract
TWIN SISTER OF FT (TSF) is a member of a small gene family in Arabidopsis, which includes FT. Since TSF is the closest homolog of FT in the family, it is likely that TSF plays a similar role as a floral promoter.
TSF expression was regulated by CO and showed diurnal oscillation. In some flowering-time mutants, expression levels of TSF changed in a similar manner to FT. These results suggest that TSF may play a role as a floral pathway integrator. In agreement with this, presumably RNA-null allele tsf-1 due to a T-DNA insertion enhanced the phenotype of loss-of-function allele of FT. However, with functional FT, tsf-1 did not have significant effect on flowering time under long-day conditions. Interestingly, TSF and FT expression patterns did not overlap. Although TSF act redundantly in determination of flowering time with FT, there may be a functional differentiation between the two genes.
