Vernalization is a response to the winter cold to acquire the competence to flower in next spring. VERNALIZATION INSENSITIVE 3 (VIN3) is a PHD-finger protein that binds to modified histones in vitro. VIN3 is induced by long-term cold and is necessary for Polycomb Repression Complex 2 (PRC2)-mediated tri-methylation of Histone H3 Lysine 27 (H3K27me3) at the FLC locus in Arabidopsis. An alteration in the PHD-finger domain of VIN3 changes the binding specificity of the PHD-finger domain of VIN3 in vitro and results in an accelerated vernalization response in vivo. The acceleration in vernalization response is achieved by increased enrichments of VIN3 and tri-methylation of Histone H3 Lysine 27 (H3K27me3) at the FLC locus without invoking the increased enrichment of Polycomb Repressive Complex 2. This result indicates that the binding specificity of the PHD-finger domain of VIN3 plays a role in mediating a proper vernalization response in Arabidopsis. Furthermore, this work shows a potential that the alteration of PHD-finger domains could be applied to alter various developmental processes in plants.
