The lineage specific VIN3 family of proteins includes VIN3, VIN3-like1-3 (VIL1-3) and similar proteins. They contain a plant homeodomain (PHD) finger, and collectively repress different sets of members of the Flowering LOCUS C (FLC) gene family during the course of vernalization []. Both VIN3 and VIL1 are required for modifying the histone architecture of the MADS box floral repressor FLC in response to prolonged cold exposure in Arabidopsis []. VIN3 is required for both Histone H3 Lys 9 (H3K9) and Histone H3 Lys 27 (H3K27) methylation at FLC chromatin, ultimately leading to its repression. It is regulated by the components of Polycomb Response Complex2 (PRC2), which trimethylates histone H3 Lys 27 (H3K27me3) [, ]. VIL1 appears to play a prominent role in regulating FLC by vernalization []. VIL2 acts together with PRC2 to repress the floral repressor MAF5, an FLC clade member, in a photoperiod-dependent manner to accelerate flowering under non-inductive photoperiods [, ].
