Cold Acclimation and Gene Expression

By Michael Chen · October 18, 2026

The Cold Acclimation Process

Cold acclimation is the physiological and molecular process by which plants increase their freezing tolerance in response to non-freezing low temperatures (typically 2 to 10°C). This process takes days to weeks and involves massive reprogramming of gene expression — in Arabidopsis, over 1,000 genes change their expression levels during cold acclimation.

The CBF Pathway

The C-repeat Binding Factor (CBF) pathway is the master regulatory circuit for cold acclimation. When temperatures drop, the ICE1 transcription factor activates CBF genes, which in turn activate hundreds of COR (Cold-Regulated) genes. COR genes encode proteins that stabilize cell membranes, act as antifreeze, and protect cellular structures from ice damage. This cascade was discovered in the 1990s and remains one of the best-characterized plant signaling pathways.

Antifreeze Proteins

Plants produce specialized antifreeze proteins (AFPs) that bind to the surface of ice crystals and inhibit their growth. Unlike animal antifreeze proteins found in Arctic fish, plant AFPs are modified versions of enzymes involved in cell wall degradation — chitinases and glucanases that evolved a new function. These proteins prevent small ice crystals from growing into large, cell-destroying structures.

LEA Proteins and Cellular Protection

Late Embryogenesis Abundant (LEA) proteins are highly hydrophilic proteins that accumulate during cold acclimation and drought stress. They function as molecular shields, preventing protein aggregation and membrane fusion during dehydration. LEA proteins are intrinsically disordered — they lack a fixed three-dimensional structure — which allows them to interact with many different cellular components and stabilize them against cold damage.

Sugar Accumulation as Cryoprotection

Cold-acclimated plants accumulate soluble sugars — particularly sucrose, raffinose, and fructans — that serve dual functions as cryoprotectants and osmolytes. Sugars lower the freezing point of cell sap, stabilize membranes and proteins, and replace water molecules around macromolecules during dehydration. The sweet taste of cold-hardened kale and Brussels sprouts is a direct result of this sugar accumulation.

Membrane Remodeling

Cell membranes are the first structures damaged by freezing. Cold acclimation triggers desaturation of membrane fatty acids by desaturase enzymes, increasing the proportion of unsaturated bonds that keep membranes fluid at low temperatures. Additionally, sterol composition changes to maintain membrane integrity. Plants that cannot remodel membranes efficiently are more susceptible to cold damage.

Proline and Compatible Solutes

The amino acid proline accumulates to high concentrations during cold acclimation, serving as an osmoprotectant, a reactive oxygen species scavenger, and a protein stabilizer. Proline biosynthesis is upregulated by the P5CS enzyme, while proline degradation is downregulated by suppressing ProDH. This dual regulation creates a rapid and dramatic increase in cellular proline levels.

Epigenetic Memory of Cold

Recent research shows that cold acclimation involves epigenetic modifications — DNA methylation and histone changes — that create a molecular memory of cold exposure. This memory allows plants to respond faster and more strongly to subsequent cold events, a phenomenon called priming. Some epigenetic marks can even be transmitted to offspring, providing transgenerational cold tolerance.