Among the many foods that are included within the umbrella of the Mediterranean diet, citrus fruits have traditionally occupied a privileged place. However, an investigation has determined that its true origin is not in the most western European crops, but is Asian. What’s more, they all have a common origin.
Despite the fact that citrus fruits are one of the most commercialized types of fruits in the world, there was something that confused scientists, and that made it difficult to classify them: and it is their high level of hybridization.
Oranges, mandarins, lemons, grapefruits … and thus up to 60 varieties of citrus were analyzed by a team of scientists, who concluded that their origin was unique: a type of tree 8 million years ago, in a region in the Himalayan foothills. Specifically, the area of origin of this tree, from which all citrus fruits originated, was a tropical rainforest in the southeast of the Himalayas, in a region that includes eastern Assam, northern Myanmar and western Yunnan.
“Our analyzes suggest that ancestral citrus species underwent a sudden speciation event during the late Miocene, about 8 million years ago,” the researchers detail in the study, published in the journal Nature.
This speciation coincided with a pronounced transition from wet monsoon conditions to a drier climate.
Thus, there was a separation that gave rise to the complex variety of citrus that exist today, distinguishing pure and hybrid types; which also implies a complex process of “domestication” by the human being.
“The first attempts to domesticate these fruits were based on asexual propagation through seeds without fertilization and the deliberate selection of specific traits,” reveals the researcher Manuel Talón to the SINC Agency, lead author of the research and scientist at the Valencian Institute of Agrarian Investigations (IVIA).
A reformulation of the genus ‘Citrus’
The new work challenges previous proposals for citrus taxonomy. In fact, scientists compare the complex mixing history of human-grown citrus with that experienced by other well-recognized crops, such as rice and corn, and even other fruit trees, such as apples and grapes.
Other groups of cultivated citrus, the hybrids, originated from hybridizations of two pure parental species.
In general, the work presents ideas that give the key about the origin, evolution and domestication of citrus fruits, and the genealogy of the most important wild and cultivated varieties.
Taken together, these findings outline a new evolutionary framework for these fruit crops : a scenario that challenges current taxonomic and phylogenetic thinking, and points toward a reformulation of the genus Citrus.
