Despite the fact that wine and grapes were very important in the culture, the truth is that until now it has been difficult to confirm when the vines were domesticated and where this happened. One reason is that extensive genetic sequencing analyzes of the castes have not been carried out.
An international team of researchers carried out this genetic study, the largest to date carried out on different varieties, which includes samples from undocumented specimens in private collections.
The work, which was carried out with the added difficulty of Covid-19 lockdowns and restrictions, provides new insights into how, when and where wine vines and table grapes were domesticated.
Until now, some hypotheses suggested that the cultivated vine (Vitis vinifera) had only been domesticated in Western Asia. It was believed that all varieties of wine came from it and that it would have been domesticated before the advent of agriculture. Another hypothesis that was assumed to be true was that the vines for wine were older than the vines for table grapes.
It is the largest genetic study carried out to date on different grape varieties
This study, published in the journal Science and led by Yang Dong and his team, would dismantle both theories. His work describes that there were two vine domestication events in two different locations, West Asia and the Caucasus region, separated during the last glacial advance.
In a related paper, Robin Allaby of the University of Warwick explains: “Despite being more than 1,000 kilometers apart, the two domestication processes appear to have occurred simultaneously with a high degree of shared selection signatures on the same genes.”
The researchers also showed that the two events occurred simultaneously, throwing to the ground the thesis that the vine was cultivated first. According to their results, they occurred 11,000 years ago, with the onset of agriculture, and about 4,000 years later than some previous studies have shown.
With two domestication events, there is a third possibility, that both grape types arose at the same time. And that’s exactly what the reviews showed.
Wei Chen, co-author of the study
“Whether table grapes or wine grapes came first is a question arising from the initial belief of a single domestication event. We now know that the original belief is no longer true. With two domestication events, there is a third possibility, which both types of domesticated grapes came out at the same time. And that’s exactly what the analyzes showed,” study co-author Wei Chen told SINC.
This photo shows wild vine flowers in the Crimean mountains. / Svitlana Goryslavets
To determine this chronology and calculate when events occurred, they used the Relative Cross Coalescence Rate (RCCR) estimate, which indicates when two populations split.
“In our case, the process of domestication can be seen as the cultivated grape population diverging from its wild ancestral population. So we used RCCR to infer the time of domestication, and the estimate for both events was around 11,000 years ago , that is, they happened at the same time in the past”, says Chen.
a great sample
The authors generated a high quality chromosomal scale reference genome of the wild vine ancestor Vitis sylvestris. They subsequently sequenced more than 3,000 individual samples of vine plants collected from a wide variety of locations across the world, including wild specimens and private collections.
Covers all wild vine growing areas and the main cultivated vine areas
“It is the largest set of wild and cultivated vineyards to date, covering all the areas where the first are cultivated and the main areas where the latter are cultivated in the world”, he clarifies.
Chen recognizes that, thanks to his collaborators, they managed to obtain old and local varieties. For example, many of these samples originating from ancient vineyards in Armenia turned out to be undocumented varieties.
Research team in Israel. / Photo courtesy of the author
For the research, they used samples from countries such as Japan, Korea, India, Pakistan, Afghanistan, Turkmenistan, Kyrgyzstan, Uzbekistan, Kazakhstan, Azerbaijan, Iran, Dagestan (Russia), Georgia, Yemen, Syria, Lebanon, Jordan, Israel, Egypt , Cyprus , Turkey, Bulgaria, Romania, Ukraine, Moldova, Serbia, Hungary, Greece, Albania, Croatia, Montenegro, Czech Republic, Germany, Austria, Slovenia, Italy, Tunisia, Algeria, Australia, South Africa, Argentina, USA, United Kingdom, Switzerland, France and also the Iberian Peninsula, including Spain and Portugal.
The study also found that wine grapes in Europe originate from table grapes domesticated in West Asia. “The process consists of crossing table grapes with local wild grapes, as the first farmers traveled to Europe to settle down,” adds Chen.
Peculiarities of the white grape
Thanks to the study, it was possible to identify some genes involved in grape domestication —which improve flavor, color and texture— that can help winemakers improve wine today and make varieties more resistant to climate change and other stresses.
In muscatel grapes, most varieties were left with a single copy of a flavor-associated variation.
Among their discoveries, they uncovered more details about the genetics underlying white grape color and the ancient taste of muscat. As they indicate, at least one allele underlying muscat flavor can be detrimental to plant health.
“Desirable traits are usually linked to genetic variations. Initially, they are rare in a population, and as people select for them, they become more and more prominent. If things go well, everyone gets two copies of the variations .” says Chen.
“In muscat grapes, most varieties are left with only one copy of a flavor-associated variation. This implies that two variations can be too many for one grape plant. Unfortunately, we don’t know the molecular mechanism of this observation,” he concludes.
Could there have been more than two events?
While the study speaks of two domestication events, it doesn’t close the door on there being more. The team has raised a third that they want to explore.
“We have to analyze a region in Central Asia (Fergana Valley) in the future. Unfortunately, we could not test whether this location is a third domestication center, because we need reliable wild grapes from this region,” concludes the researcher.
Yang Dong and others. “The largest genetic analysis of vine varieties ever done reveals how glacial cycles shaped grape domestication and the rise of wine.” Science.