Transcriptional activator involved in the FRIGIDA-mediated vernalization pathway, but not in the autonomous flowering pathway. Acts cooperatively with FRI (FRIGIDA) or FRL1 (FRIGIDA-LIKE 1) to promote FLC (FLOWERING LOCUS C) expression. Required for the stabilization of the FRI-C complex. Component of the transcription activator complex FRI-C composed of FRI, FRL1, SUF4, FLX and FES1. Interacts with FLX, (via C-terminus) with FRI (via C-terminus), and with RIN1, a component of the SWR1 chromatin-remodeling complex. Expressed in root and shoot apices and vasculature. The zinc-finger motif is essential for transcription activation.