Rockmelons originated in Asia, not Africa

A recent study has revealed that that the cultivated rockmelon originated in Asia, not Africa, as previously thought.

The research compared the DNA of melons around the world and also found new species that could provide plant breeders with a goldmine of new traits.

Until now, scientists have thought the cultivated rockmelon (Cucumis melo) originated in Africa because morphological studies suggested the closest relative was there, said Ian Telford, of the University of New England.

But Telford and colleagues have now found previously overlooked species of melons in Australia and around the Indian Ocean, which are genetically more similar to rockmelon than the African melons.

"Morphology has led us astray so often," ABC Science quoted Telford as saying.

The researchers used DNA sequence data to compare some 100 melons and cucumbers across the world.

The researchers found seven new species of cucumis in Australia, including a wild melon C. picrocarpus, widespread throughout the tropics and sub-tropics.

Surprisingly, this 'sister species' turns out to be the most genetically similar to our cultivated rockmelon, said Telford.

He said C. picrocarpus would have diverged from C. melo about 3 million years ago and its ancestor would have come from Asia.
The researchers have also found evidence confirming suspicions that the cucumber originated in Asia.

"There are many more wild relatives of cucumber than were suspected, particularly in Australia," said Telford, who found six new wild cucumbers.

Together with the rockmelon, the cucumber is most likely to have originated from the Himalayan region, the researchers said.

Telford said the discovery of so many extra species of melon and cucumber in Asia and Australia is a boon for plant breeders.

"For plant breeders, these wild populations may have traits that can be transferred to the cultivated plants."

The findings were published in the Proceedings of the National Academy of Sciences.