Madrid. Scientists have sequenced the highest-quality reference genome yet of the most popular coffee variety, Arabica, revealing secrets of its lineage, which spans millennia and continents.
Their findings, published in Nature Geneticsthey suggest that Coffea arabica It was developed more than 600 thousand years ago in the forests of Ethiopia through natural crossing between two other coffee species. The study found that the arabica population rose and fell during periods of Earth’s warming and cooling for thousands of years, before being cultivated in Ethiopia and Yemen, and then spread around the world.
We have used genomic information from plants alive today to go back in time and paint the most accurate picture possible of the long history of Arabica, as well as to determine how modern cultivated varieties are related to each other.
says study co-author Victor Albert, professor in the Department of Biological Sciences at the University at Buffalo, in a statement.
Coffee giants like Starbucks and Tim Hortons exclusively use beans from Arabica plants to brew the millions of cups of coffee they serve every day; However, partly due to low genetic diversity stemming from a history of inbreeding and small population size, arabica is susceptible to many pests and diseases and can only be grown in a few places in the world where pathogen threats are lower. and the weather conditions are more favorable.
A detailed understanding of the origins and breeding history of contemporary varieties is crucial to developing new arabica cultivars better adapted to climate change.
Albert explained.
Using their new reference genome, which was achieved with cutting-edge DNA sequencing technology and advanced data science, the team sequenced 39 varieties of Arabica and even an 18th-century specimen used by Swedish naturalist Carl Linnaeus to name the species.
The reference genome is now in a publicly available digital database.
Although there are other public references about Arabica coffee, the quality of our team’s work is extremely high.
says one of the co-leaders of the study, Patrick Descombes, senior genomics expert at Nestlé Research. We use next-generation genomic approaches, including long- and short-read high-throughput DNA sequencing, to create the most advanced, complete and continuous Arabica reference genome to date.
.
Arabica is the source of approximately 60 percent of the world’s coffee products and its seeds help millions of people start their day or stay up late. However, the initial crossing that created it was done without any human intervention.
Arabica was formed as a natural hybridization between Coffea canephora y Coffea eugenioides, in which he received two sets of chromosomes from each parent. Scientists have had difficulty determining exactly when and where this allopolyploidization event took place, with estimates ranging from 10,000 to a million years ago.
To find evidence of the original event, the University at Buffalo researchers and their partners ran their various arabica genomes through a computational modeling program looking for signatures of the species’ basis.
The models show three demographic bottlenecks during the history of arabica; the oldest occurred about 29 thousand generations ago (or 610 thousand years). This suggests that Arabica formed sometime earlier, between 610,000 and one million years ago, the researchers say.
In other words, the crossbreeding that created Arabica was not something humans did
Albert establishment. It is quite clear that this polyploidy event predates modern humans and coffee cultivation.
.
Coffee plants were long thought to have developed in Ethiopia, but the varieties the team collected around the Great Rift Valley, which stretches from southeast Africa to Asia, showed a clear geographic divide. All wild varieties studied originated on the western side, while all cultivated varieties originated on the eastern side, closer to the Bab al-Mandab Strait, which separates Africa and Yemen.
This would coincide with evidence that coffee cultivation may have begun primarily in Yemen, around the 15th century. The Indian monk Baba Budan is believed to have smuggled out the legendary seven seeds
of Yemen around 1600, establishing Indian arabica crops and setting the stage for coffee’s global reach today.
It seems that the diversity of Yemeni coffee may be the founder of all the main current varieties
Descombes estimated. Coffee is not a crop that has been heavily crossed, like corn or wheat, to create new varieties. People mainly chose a variety they liked and then grew it. So the varieties we have today have probably been around for a long time.
.