We used to think that European wine grapes were cultivated locally, independently of grape domestication in western Asia, but grape genetics suggests otherwise
21 December 2021
Grapes used to make common European wines may have originated from grapevines that were first domesticated in the South Caucasus region of western Asia. As these domesticated grapes dispersed westwards during the Greek and Roman times, they interbred with local European wild populations, which helped the wine grapes adapt to different European climates.
The origins of grapes (Vitis vinifera) that are used in Europe and elsewhere to produce wines such as Merlot, Chardonnay and Pinot Noir have long been debated.
It has been proposed that European wine grapes arose from the cultivation of wild European populations (V. vinifera subspecies sylvestris), independently of the original domestication of grapes in western Asia around 7000 years ago.
But a genetic analysis carried out by Gabriele Di Gaspero at the Institute of Applied Genomics in Udine, Italy, and his colleagues suggests that European wine grapes actually originated from domesticated grapes (V. vinifera subspecies sativa) that were initially grown for consumption as fresh fruit in western Asia.
The team sequenced the genomes of 204 wild and cultivated grape varieties – to cover the range of genetic diversity in cultivated grapes – and compared how similar their genetic sequences were to one another.
This revealed that as western Asian table grapes spread westwards across the Mediterranean and further inland into Europe, they interbred with wild European grape populations that grew nearby.
“The wild plants grew close to vineyards and interbred – this was unintentional. But the results of the breeding created adaptive traits that were likely selected by humans intentionally,” says Di Gaspero. “By bringing together this genetic evidence and existing historical evidence, the introductions in southern Europe and inland likely occurred in Greek and Roman times, although we don’t know more specific dates.”
By modelling how the ancestry of the grapes in different regions of Europe related to aspects of the local climate such as temperature and precipitation, the team discovered that European wild grapes probably contributed traits that enabled the ancestral grape vines to adapt to different regions as they moved westwards from Asia.
The team also found evidence of the effect that domestication had on grape genetics.
In wild grape varieties, a larger seed makes a larger berry because grape seeds produce a growth hormone called ethylene. But for human consumption, a larger berry-to-seed ratio is desirable. The team found that an enzyme not found in the berries of wild varieties was present in the berries of domesticated varieties. In other plants, the enzyme is known to help berries grow in response to ethylene, which suggests it does the same in grapes.
Understanding which genes encode favourable traits in grapes can allow us grow better grape crops, says Di Gaspero.
Journal reference: Nature Communications, DOI: 10.1038/s41467-021-27487-y
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