Family Tree of Lemon and Orange

Citrus fruits have a worldwide high value, but they were a lot more valuable about 8 million years ago because they only grew on the foothills of the Himalayas. Thankfully, neither modern humans nor trade existed then. About 4 million years later, they diversified and spread across Southeast Asia, and to Australia, and diversified once again: from orange to mandarin, from lime to bergamot…

These information come from genome analyses on 60 different varieties. The study, published in Nature, asserts that the modern day citrus trees originated from a region that includes the eastern area of Assam, northern Myanmar, and western Yunnan. When the climate changed millions of years ago, with monsoons getting weaker and weather getting dryer, trees found the opportunity to spread beyond the Himalayas.

Fossil records are scarce, but not non-existent. The 8-million-years-old fossil of a citrus leaf found in southwestern China supports the data from genetic studies.

Future guaranteed

Genetic maps based on analyses will assist in showing which species are more resilient against pests, and may even help scientists to develop new citrus varieties. Maybe we will have tastier, juicier, or seedless citrus fruits on our tables.

Besides, we are in a new climate change period. The research may help ensure that these valuable citrus trees and their fruits survive this period with minimum damage.