Population genomics of transcontinental grapevines reveals divergent evolutionary trajectories and cis-regulatory mechanisms underlying cold adaptation
This study integrates transcontinental population genomics and functional validation to reveal that divergent evolutionary trajectories in grapevine cold adaptation are driven by winter thermal regimes, specifically through a cis-regulatory mechanism where *vvi-miR169g* negatively regulates cold tolerance by cleaving *NF-YA* transcripts.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Plants that live for decades face a different challenge than those that live for a single season. While an annual plant can simply wait for better weather to return next year, a perennial tree or vine must survive the harsh conditions of winter while remaining alive to grow again in the spring. For grapevines, which are the foundation of a global industry, surviving freezing temperatures is a matter of life and death. The ability to withstand cold is not just about having thick bark; it is a complex biological process involving how the plant reads its own genetic instructions. Scientists have long known that plants from different parts of the world have evolved different ways to handle the cold, but the specific genetic switches that allow some vines to survive freezing while others perish have remained hidden. Understanding these mechanisms is crucial as global climates shift, threatening to push many traditional wine-growing regions beyond their limits.
A team of researchers at Shanghai Jiao Tong University has now peeled back the layers of this mystery by examining the DNA of grapevines from across the globe. They gathered a massive collection of 223 different grapevine samples, ranging from ancient wild varieties found in North America to the cultivated vines grown in Europe for thousands of years. By sequencing the entire genetic code of these plants and comparing them against the climates where they naturally grow, the scientists uncovered a striking divide in how these two groups evolved. The European vines, which were bred for fruit quality, followed one evolutionary path, while the wild North American vines, which had to survive brutal winters on their own, followed a completely different one. The study reveals that the wild vines developed a sophisticated system of post-transcriptional regulation, a method of controlling genes that happens after the genetic code has been read, allowing for a flexible and rapid response to freezing temperatures.
The researchers discovered that the primary driver of this evolutionary split was the temperature of the coldest month of the year. Using advanced statistical models, they showed that this specific thermal filter shaped the genetic makeup of the wild North American populations far more than the distance between them or other environmental factors. In contrast, the European vines, which were domesticated and moved by humans, showed signs of selection focused on fruit sweetness and color rather than extreme cold survival. When the team subjected these different vines to a controlled cold stress test, the difference became physically visible. The North American vines maintained their photosynthetic machinery, the engine that powers the plant, even after 24 hours of freezing. The European vines, however, saw their photosynthetic efficiency collapse rapidly, their leaves turning brown and dying.
At the heart of this difference lies a specific genetic switch located on chromosome 8. The researchers pinpointed a region just before a gene called vvi-miR169g, which acts as a master regulator. This gene negatively regulates cold tolerance by targeting and cleaving transcripts of defense-related genes. In the cold-sensitive European vines, specific variations in the promoter region of this gene create a "de novo" motif that likely drives higher expression, keeping the plant's defenses suppressed. In contrast, the cold-hardy North American vines possess a different genetic variant (a specific haplotype) in this same region that allows for a more balanced regulation, preventing the excessive suppression of defense mechanisms. The study confirmed that this gene works by targeting another set of genes responsible for antioxidant production. When the cold hits, the North American vines maintain a state where the vvi-miR169g gene does not over-suppress these defenses, allowing the plant to produce antioxidants that protect its cells from damage. The European vines, with their specific promoter variations, fail to make this adjustment, leaving them vulnerable to the freezing stress.
To prove this mechanism was real, the scientists performed experiments where they artificially altered the gene in grapevine tissue. When they increased the activity of the vvi-miR169g gene, the plants became highly sensitive to cold, suffering severe damage. Conversely, when they silenced the gene, the plants became significantly more resistant to freezing, maintaining their health and photosynthetic power even under stress. This confirmed that the gene acts as a negative regulator, a brake on the plant's cold tolerance, and that removing this brake is key to survival. The study also looked at the future, using computer models to simulate how these genetic patterns would hold up under predicted climate change scenarios. The results suggest that while some wild North American populations might struggle as winters warm, certain European varieties could face localized risks in traditional wine regions if extreme cold events still occur.
This work provides a clear map of how a perennial crop adapts to its environment, moving beyond simple observations of survival to the molecular level. It shows that the difference between a vine that survives a freeze and one that dies often comes down to a few specific changes in the DNA sequence that control how genes are turned on and off. By identifying these precise genetic targets, the study offers a new path for breeding grapevines that can withstand the unpredictable weather of a changing world. The findings suggest that by tweaking these regulatory switches, scientists could potentially enhance the cold tolerance of high-quality European varieties without sacrificing their fruit, ensuring the future of viticulture in a warming planet.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.