“We are really confident in saying this is the closest relative,” Dr. Chomicki said.
The Kordofan melon and the modern watermelon most likely arose from a long-ago wild melon, the results suggest. Farmers would have realized this melon was sweeter than others and bred it into new, tasty varieties.
Researchers still don’t know, however, who took this wild melon ancestor and turned it into what’s on the tomb wall in Saqqara, or set it on the path to what we eat today. Dr. Chomicki and his colleagues are planning to sequence the genomes of melon seeds found in African archaeological sites to try to determine where and when humans coaxed early watermelons into a more edible form.
The wild relatives of domesticated crops can be sources of fresh, interesting genes for breeders. A new color, a hardy resistance to drought or a new way to fight off blight are the kinds of treasures wild plants can bring to the gene pool of domesticated varieties.
Even varieties that are closer to the source, as the Kordofan melon may be, can help. The new study found that it has different forms of genes related to disease resistance than the standard watermelon.
It’s not clear if there are still any wild versions of the Kordofan melon or its relatives growing in Sudan, Dr. Chomicki said. In the 1800s, the German botanist wrote, there were patches of the melons growing wild. But this region, which is near Darfur, is now difficult for researchers to gain access to because of violence.
Many wild relatives of crop plants are facing extinction around the world, a result of human disturbance and climate change. When they go, they take opportunities to improve domestic varieties with them.
Dr. Chomicki has never tasted the Kordofan melon — for their analysis, the team members had to rely on samples collected by others. The tales of its sweet flavor, the telltale sign that it may have had a story to tell about modern watermelon, are still secondhand.
“But I still have some seeds,” he said, “so I will plant them and see.”