How Arabidopsis Remembers Winter Through DNA Packaging

A plant can carry a record of winter into warmer days. In winter-annual Arabidopsis thaliana, prolonged cold helps switch off a gene that restrains flowering. The altered state can outlast the temperature that produced it. Biologists call this a form of epigenetic memory: an environmental experience changes how genetic information is used. [2]

The finding at a glance

• Prolonged cold can release a flowering brake by silencing FLC. [2]
• The 2025 study linked a regulator, VRN1, to changes in DNA packaging. [1]
• The experiments used Arabidopsis; broad agricultural benefits require separate testing.

Flowering has a molecular brake

The gene FLOWERING LOCUS C, usually shortened to FLC, encodes a protein that represses flowering. Its role was established well before the 2025 work. A 1999 study found that loss-of-function mutations caused early flowering, while experimentally increasing FLC expression could delay flowering. Those interventions made the gene’s effect testable rather than merely associating its activity with the season. [3]

A brake is a useful analogy because removing restraint does not dictate the entire journey. Silencing FLC makes the plant more able to respond to flowering-promoting conditions. The prolonged-cold process is called vernalization. Researchers use Arabidopsis as a model to investigate how temperature history is integrated with developmental decisions, rather than assuming that a single warm afternoon is enough to announce spring. [2]

DNA packaging helps control access to genes

DNA in a cell is associated with proteins, forming chromatin. Histones are central packaging proteins: DNA wraps around them in units called nucleosomes. An illustration often presents these units as beads along a string. That picture is a useful starting point, provided the beads are understood as movable molecular assemblies rather than fixed ornaments. [7]

Packaging affects which parts of the DNA are accessible to the machinery that uses genetic instructions. It is helpful to separate the written sequence from its physical organization. The same sequence can be used differently as protein associations and local structure change. A molecular memory therefore need not be a new mutation in the DNA letters. Here, the relevant question is how a regulated state persists after cold exposure ends.

What the 2025 experiments added

Miguel Montez and colleagues published their peer-reviewed study in Nature Communications on 1 July 2025. They compared Arabidopsis genetic lines during cold and warm recovery. Gene-expression and chromatin assays, nucleosome mapping and molecular simulations examined the regulator VRN1 and FLC silencing. [1]

Cold shifted a nucleosome near FLC’s transcription start. VRN1 mutants accumulated extra H2A.Z, a histone variant, and showed compromised silencing. The authors linked nucleosome behaviour to the switch into a repressed state. Their simulations supported a structural model but omitted VRN1 binding and PRC2 activity. [1]

The combination matters because the methods answer different questions. A gene-expression assay measures output; a chromatin assay examines the associated molecular state. A mutant comparison changes a biological component, while a simulation explores how a proposed arrangement could behave. Agreement makes an explanation more useful, but a simulated configuration still needs experimental evaluation. It is not an image of a structure directly observed inside every cell.

How a cold period becomes a lasting state

The memory system includes the Polycomb Repressive Complex 2, or PRC2. This protein complex generates a histone modification called H3K27me3, associated with stable gene silencing. The name refers to a chemical mark on histone H3. Describing it as an epigenetic mark does not mean that the underlying DNA sequence has been rewritten. [4]

A 2011 study combined mathematical modelling, chromatin measurements and a gene-activity reporter. It found that longer prior cold increased the fraction of cells showing stable FLC silencing after return to warmth. The model’s switching behaviour was tested with the reporter system. This explained how a gradual response at the plant level can emerge from switching at individual loci, rather than every copy of a gene becoming uniformly quieter. [4]

This distinction helps explain the word memory. The present state depends partly on the past conditions, even after those conditions change. Such persistence is a measurable property of a biological regulatory system. It does not require the organism to have a mental picture of winter or to consciously predict what comes next.

Another 2025 study examined cold-duration signalling

A separate peer-reviewed Nature Plants paper, published on 1 August 2025, investigated a different part of the mechanism in Arabidopsis. It reported that the kinase CK2 phosphorylates and stabilizes enzymes within PRC2. Prolonged cold progressively increased CK2 and cellular PRC2 accumulation, helping connect cold duration with later repression of FLC. [6]

These findings concern a signalling layer that complements the DNA-packaging question. A kinase adds phosphate groups to proteins; that can change their behaviour or stability. Protein regulation, chromatin organization and gene expression are connected levels of explanation. Identifying one useful layer does not make the rest dispensable, nor does it establish one identical temperature-response mechanism across all plants. [6]

Does the next generation inherit that winter?

Persistence within a plant and inheritance by offspring are different problems. FLC is normally reactivated during seed development, allowing a new generation to require its own vernalization. A 2014 study investigated this reset and identified a mutation in the protein ELF6 that impaired FLC reactivation. The mutant offspring retained a partially vernalized state. [5]

The researchers connected the defect to reduced activity of an enzyme that removes H3K27me3. Their findings show that resetting is itself an active biological process. They also caution against treating all epigenetic memory as automatically inherited: a state can be maintained through growth yet normally erased as the next generation develops. [5]

What this research does not establish

The featured experiments concern a defined Arabidopsis system under controlled conditions. They do not demonstrate conscious recollection, a universal mechanism in every species, or a ready-made way to improve crop yields. The structural simulations also simplify a crowded cellular environment. Their value lies in producing explanations that can be compared with measurements and challenged with further experiments.

Real winters fluctuate. Daytime warmth, night-time cold and the duration of exposure can differ from laboratory schedules. The John Innes Centre’s research account emphasizes the importance of understanding how plants integrate these variable signals. That makes field validation an essential part of applying a mechanistic result, rather than an optional final illustration. [2]

Why this matters for biotechnology

One practical research direction would compare related plant varieties under realistic temperature profiles, measuring flowering time alongside molecular markers. Another would test whether manipulating a candidate regulator changes the stability of cold-induced silencing without disrupting other development. These are proposed evaluation steps, not agricultural benefits established by the 2025 study.

For biotechnology, the story illustrates how environment, protein regulation and the physical handling of DNA can meet at a developmental decision. A useful model must explain both the initial response and its persistence. Arabidopsis offers a particularly well-studied example: an experience of cold can leave a molecular state that continues to influence what the plant does after temperatures rise.

Sources

1. Montez M et al. Cold-induced nucleosome dynamics linked to silencing of Arabidopsis FLC. Nature Communications 16, 5550 (2025). Published 1 July 2025. https://doi.org/10.1038/s41467-025-60735-z. Institutional research summary.
2. John Innes Centre. What is vernalization and how do plants remember winter? Original research-team explanation, 15 July 2020. https://jic.ac.uk/blog/what-is-vernalization-and-how-do-plants-remember-winter/.
3. Michaels SD, Amasino RM. FLOWERING LOCUS C encodes a novel MADS domain protein that acts as a repressor of flowering. The Plant Cell 11, 949–956 (1999). https://doi.org/10.1105/tpc.11.5.949.
4. Angel A, Song J, Dean C, Howard M. A Polycomb-based switch underlying quantitative epigenetic memory. Nature 476, 105–108 (2011). https://doi.org/10.1038/nature10241.
5. Crevillén P et al. Epigenetic reprogramming that prevents transgenerational inheritance of the vernalized state. Nature 515, 587–590 (2014). https://doi.org/10.1038/nature13722.
6. Zeng X et al. CK2 kinase–PRC2 signalling regulates genome-wide H3K27 trimethylation and transduces prolonged cold exposure into epigenetic cold memory in plants. Nature Plants 11, 1572–1590 (2025). Published 1 August 2025. https://doi.org/10.1038/s41477-025-02054-1.
7. National Human Genome Research Institute. Chromatin. Talking Glossary of Genetic Terms. Updated 27 October 2026. https://www.genome.gov/genetics-glossary/Chromatin.