Vernalization, sensing of prolonged cold, is important for seasonal flowering in eudicots and monocots. While vernalization silences a repressor (​FLC, MADS-box transcription factor) in eudicots, it induces an activator (​TaVRN1, an AP1 clade MADS-box transcription factor) in monocots. The mechanism for ​TaVRN1 induction during vernalization is not well understood. Here we reveal a novel mechanism for controlling ​TaVRN1 mRNA accumulation in response to prolonged cold sensing in wheat. The carbohydrate-binding protein ​VER2, a jacalin lectin, promotes ​TaVRN1upregulation by physically interacting with the RNA-binding protein ​TaGRP2. ​TaGRP2 binds to ​TaVRN1 pre-mRNA and inhibits ​TaVRN1 mRNA accumulation. The physical interaction between ​VER2and ​TaGRP2 is controlled by ​TaGRP2 O-GlcNAc modification, which gradually increases during vernalization. The interaction between ​VER2 and O-GlcNAc-​TaGRP2 reduces ​TaGRP2 protein accumulation in the nucleus and/or promotes ​TaGRP2 dissociation from ​TaVRN1, leading to ​TaVRN1 mRNA accumulation. Our data reveal a new mechanism for sensing prolonged cold in temperate cereals.