A massive study that sequenced the DNA of more than 3,525 grape cultivars from around the world, published this month in the journal Science, has upended the history of how humans first domesticated grapes for winemaking and may reveal important information about how a few shriveled ancient Israeli grape seeds could save the future of winemaking from global warming.
Dr. Wei Chen of the Yunnan Agricultural Institution in southern China first started sequencing the DNA of grape cultivars in 2017 for a study of Chinese grape varieties. He and his lab sequenced almost 500 grapevines and found that through the DNA they could track the way different grape varieties migrated across the country, and how cultivars split off from one another to form distinct varieties.
He and his colleagues realized that if they could get their hands on enough varieties’ DNA, they would be able to map the migration of different varieties throughout the world, and throughout time, pinpointing when humans domesticated grapes for the first time.
The concept of creating a global study started off as a spitball idea among friends. But in 2019, Chen and his lab decided to take the plunge and launched an international research project focusing on grape cultivars.
“We started to reach out to our friends and colleagues in Europe, and we got the first batch from Germany, France, and Spain,” said Chen.
Colleagues sent dried young leaves from various local grape varieties, so Chen’s lab could extract and sequence the DNA, or they sequenced the DNA of local varieties themselves and sent Chen the results.
“Then colleagues from Europe started to call up their friends and colleagues, and we just got more and more people into this international collaboration,” said Chen.
Within a few months, Chen’s lab got to work sequencing the DNA and looking for patterns after they received samples from 90 scientists in 70 countries of both wild and domesticated grapes — with the Israeli contingent being the largest.
Grapes that share more DNA are more closely related, while those that have little DNA in common are less related. Tracking unique bits of DNA allows Chen and his lab to trace when different varieties split off from each other, and when domesticated grapes split from wild grapes.
The results were completely different from what Chen or anyone else had expected. Previously, it was widely believed that grapes were domesticated around 8,000 years ago during the Neolithic Agricultural Revolution, likely somewhere in the Fertile Crescent.
The key result from our study is that the original belief that there was only one domestication event was completely wrong
But by tracking the DNA from the thousands of samples, Chen pinpointed that there were actually two simultaneous domestication events, each around 11,000 years ago. One happened in Western Asia, and the other happened 1,500 kilometers away in the Caucasus.