A group of scientists has succeeded in deciphering the genome and constructing a genealogical tree of one of the world's most popular coffee varieties, Arabica coffee. The results, published in the journal Nature Genetics, indicate that one of the Arabica coffee species has acquired the greatest resistance to diseases. The conclusions made by researchers from the University of Buffalo (USA), the scientists themselves are convinced, can be used in the future to develop new varieties that can cope with climate change.
A detailed map was compiled with data on the "family history" of the tree. On its basis, scientists were able to prove that Arabica arose from the natural hybridization of Coffea canephora (its variety is Robusta coffee) and Coffea eugenioides. Attempts to accurately determine where and when this event took place required the use of computer modeling of the coffee genome.
As a result, the models showed three bottlenecks in populations throughout the history of Arabica, the oldest of which occurred about 29,000 generations - 610,000 years ago. This suggests that Arabica was formed somewhere earlier, from 610,000 to one million years ago, the researchers say. "In other words, the crossing that led to the creation of Arabica was not something that people did," said Victor Albert, professor of biology at the university. "It is quite obvious that this event preceded the appearance of modern humans Homo sapiens and coffee growing."
For a long time, it was believed that coffee plants originated in Ethiopia, but the varieties that the team collected in the Great Rift Valley region, stretching from Southeast Africa to Asia, showed a clear geographical split, the scientists say. All the studied wild varieties came from the western side, while all the cultivated varieties came from the eastern side, closest to the Bab el-Mandeb Strait, separating Africa and Yemen.
The scientific research is important from the point of view of breeding new disease-resistant varieties. For example, one of the diseases of trees - coffee leaf rust - annually results in losses of from 1 to 2 billion US dollars. According to scientists, the Timor variety, also known as Robusta, was formed in Southeast Asia as a spontaneous hybrid of Arabica and one of its parents, Coffea canephora, and is more resistant. "A detailed understanding of the origin and history of selection of modern varieties is crucial for the development of new Arabica varieties better adapted to climate change," Albert noted.
Arabica coffee currently accounts for 60 to 70% of the world coffee market. The rest is Robusta, a stronger and bitter coffee.
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