Scientists sequence worlds oldest plant genome from 6,000-year-old watermelon seeds

Scientists from the Royal Botanic Gardens, Kew and partners in the U.K., Germany and the U.S. have decoded the world's oldest plant genome, using Neolithic-era watermelon seeds collected at an archaeological site in the Sahara Desert in Libya.

The study combined aspects of archaeological groundwork with cutting-edge genomics research to shed new light on the domestication of the watermelon and how our ancestors consumed the popular fruit's ancient relatives. Surprisingly, evidence suggests the Neolithic Libyans had a taste for the watermelon's seeds – a local delicacy still consumed today – but avoided the fruit's bitter-tasting flesh.

To better understand the watermelon's journey from wild plant to domesticated crop, the researchers collected and analyzed dozens of watermelon and watermelon relatives' seeds from RBG Kew's Herbarium collections. They also obtained and studied seed fossils from Libya and Sudan, radiocarbon dated (C-14) to more than 6,000 and 3,000 years ago, respectively.

The study's findings indicate the Neolithic Libyans collected or even cultivated a bitter-tasting species of watermelon, instead of the sweet-tasting crop of today. This new insight was consistent with teeth marks found on some of the oldest seeds collected in Sudan by Dr. Philippa Ryan, a postdoctoral researcher at Kew and co-author of the study.

Image source: Left: ALDONA MUELLER-BIENIEK Right: ELLY VAES, RBG KEW.