Summertime is watermelon time, and in some very cool fruit news, an ancient melon which is believed to be the closest relative and potential ancestor of the modern watermelon has been discovered by scientists.

A team led by Dr. Guillaume Chomicki from the University of Sheffield’s Department of Animal and Plant Sciences in England has recently discovered the potential great-granddaddy of the domestic watermelon, called the Kordofan melon, using DNA sequencing technology and analysis, historical data and ancient Egyptian iconography (hieroglyphics!).

The genomic work, combined with new interpretations of ancient Egyptian iconography by Chomicki and colleagues, shows that Egyptians were cultivating sweet watermelons at least 4,200 years ago.

Their findings show the melon originated in northeastern Africa, in the region of Kordofan in Sudan. The discovery gives us more insight into how the watermelon was domesticated. It could also explain why watermelons are so susceptible to disease, as the researchers’ analysis shows how key disease-resistant genes were lost as the melon was domesticated. Knowing this could help growers breed more disease-resistant watermelons in the future.

Chomicki said, “The watermelon is one of the most important tropical fruits, with over 200 million tons produced every year, but it is also very susceptible to disease. There are specific watermelon diseases, such as the watermelon mosaic virus, and they are also very sensitive to fungal infections. In conventional agriculture, they are frequently treated with fungicides and insecticides to limit virus transfer.”

He continued that their analysis clearly shows the Kordofan melon had more disease-resistant genes – and different versions of them too. “This means that the genome of the Kordofan melon has the potential to help us breed disease-resistant watermelons and allow non-GM gene editing. Achieving this would be reducing substantially pesticide use in watermelon farming.”

The new research also found that this earlier version of the watermelon was already non-bitter and farmers brought these naturally sweet forms into cultivation. This contrasts quite a bit with other species in the same family (like cucumber or squash), which lost their bitterness due to their domestication.