The new study reveals that all current citrus trees arose from a common ancestor some 15 million years ago. This fruit ancestor underwent three significant phases of evolutionary change to lead to the lemons, limes, kumquats, and oranges found around the world today.
According to the study report, biologists sequenced the chloroplast genomes of 34 species of the genus Citrus and compared them to previously examined genomes of two mandarin and two pomelo plants. With this analysis they found the citrus family could be divided into three groups that first emerged between 6.3 million and 7.5 million years ago: citron and Australian varieties, micrantha and pomelo, and mandarin and papeda. This latter group includes fruits like the Japanese yuzu.
The genetic analysis also revealed that the plants went through two subsequent evolutionary waves. Between 3.7 million and 5 million years ago, the two members of each group separated from each other, and more recently, between 200,000 and 1.5 million years ago, species such as the Fortunella group (kumquats), sour and sweet oranges, lemons, and new mandarin varieties appeared.
The study was carried out at the Centro de Investigación Príncipe Felipe (CIPF) and the Intituto Valenciano de Investigaciones Agrarias in Spain. The free-to-read research has been published in the journal Molecular Biology and Evolution. The study is titled “A phylogenetic analysis of 34 chloroplast genomes elucidates the relationships between wild and domestic species within the genus Citrus.”
