Did you answer orange? Wrong! The correct answer is Mandarin. Indeed, mandarin (Citrus reticulata), pomelo (Citrus maxima) And cedar (Citrus medica) are the three ancestral citrus fruits from which all the others were derived through crosses. We often take for granted that fruits such as oranges or lemons are “natural products” that have always existed. The reality, emerged thanks to modern genomic analyses also published in the prestigious magazine Natureis much more surprising: the vast majority of citrus fruits we find in the supermarket are not pure species, but the result of millennia of intersections, hybridizations And human selections.
The Citrus genus originates around 8 million years ago (late Miocene) in a region between north-eastern India, northern Myanmar and Yunnan (north-western China). Here, in response to a climate change that made the environment drier, the three diverged ancestral citrus fruits from which all the others descend:. The citrus fruits were then disassembled and reassembled at the genetic level with surgical precision. In particular, a great work published in the journal Nature showed that the majority of cultivated citrus fruits derive from three main ancestors:
- The mandarin (Citrus reticulata): originally from China, it has a sugary flavor and a thin skin that is easy to remove.
- The pomelo (Citrus maxima): native to south-eastern China and Malaysia. It is a large fruit with a robust structure.
- The cedar (Citrus medica): an ancient fruit, native to north-east India and Burma, almost devoid of pulp and made only of white peel (albedo).
All the rest, i.e. sweet orange, lemon, grapefruit, clementine, clementine, arise from successive crosses between these three strains. Here’s how they were born:
- TOsweet ration (Citrus × sinensis): orange is the result of an ancient cross between a pomelo and a mandarin. However, it is not a 50/50 cross. DNA analyzes show that the orange is the result of a re-cross, probably a pomelo/mandarin hybrid was crossed again with a mandarin.
- THEimon (Citrus limon): it is technically a hybrid between the cedar (which gave it its elongated shape and thick rind) andbitter orange (Citrus aurantium).
- Pompelm (Citrus paradisi) : was born from a cross between sweet orange and pomelo.
- Clementine:it is a cross between a mandarin and a sweet orange, therefore it has a “touch” of pomelo.
- Mandarin orange (tangor): it is also a hybrid between mandarin and orange but derives from heterogeneous crosses.
Another study on Nature Genetics found the genetic “cause” of the difference between citrus fruits and other fruits. Gene expression PH4 it is decisive for the quantity of citric acid in the fruit and consequently for its flavour. These quantities vary from citrus fruit to citrus fruit, small concentrations of citric acid give oranges tartness while maintaining a sweet flavor, while larger quantities give lemons a strong acidity.
