Required for the regulation of flowering time in the late-flowering phenotype. Involved in the enrichment of a WDR5A-containing COMPASS-like complex at the 'FLOWERING LOCUS C' that trimethylates histone H3 'Lys-4', leading to FLC up-regulation and RNA levels increase (PubMed:19567704). Variants with an early-flowering phenotype (Including cv. Columbia, cv. Landsberg Erecta and cv. Wassilewskija) show loss-of-function mutations of FRI. Able to delay flowering independently of FRL1 activity. Dispensable for the reactivation of FLC in early embryogenesis, but required to maintain high levels of FLC expression in later embryonic and vegetative development. Suppresses the repression of FLC by the autonomous pathway, but has no effect on the expression of the genes involved in this pathway. Homodimer. Component of the transcription activator complex FRI-C composed of FRI, FRL1, SUF4, FLX and FES1. Interacts (via N-terminus) with FRL1 and (via C-terminus) with FLX (via N-terminus), SUF4 (via C-terminus) and FES1 (via C-terminus). Interacts with ASHH2 and RIN1, a component of the SWR1 chromatin-remodeling complex (PubMed:17138694, PubMed:20711170, PubMed:21282526). Interacts with CBP20, FIP1 and FIP2 (PubMed:19429606). Expressed in ovules, but not in stamens. Not regulated by vernalization. Belongs to the Frigida family. Has been shown to be inactive in cv. Columbia (AC Q67Z93), cv. Landsberg Erecta and cv. Wassilewskija due to loss-of-function mutations. The sequence shown is from strain cv. H51.