Want tastier watermelons? All you need is the genome sequence!

Just in time for the Australian summer, juicier, sweeter, more disease-resistant watermelons could be on the way. More than 60 scientists from the United States, China and Europe have published the genome sequence of watermelon. The scientists say the information could dramatically accelerate watermelon breeding to produce more nutritious, tastier and more resistant fruit.

Domestication of the watermelon has led to a large portion of disease resistance genes being lost, the researchers said. Now the watermelon sequence is complete, they hope breeders can harness the information to recover some of the fruit’s natural disease defences.

The domesticated watermelon’s genome contains 23,440 genes, the scientists found - around the same number of genes as humans. They compared the genomes of 20 different watermelons to develop a first-generation genetic variation map for the watermelon, identifying genomic regions that have been under human selection, including those associated with colour, taste and size.

“Watermelons are an important cash crop and among the top five most consumed fresh fruits; however, cultivated watermelons have a very narrow genetic base, which presents a major bottleneck to its breeding. Decoding the complete genome of the watermelon and resequencing watermelons from different subspecies provided a wealth of information and toolkits to facilitate research and breeding,” said Zhangjun Fei, a scientist at the Boyce Thompson Institute for Plant Research at Cornell University and one of the leaders of this project.

The genome sequences of the watermelon are publicly available at the Cucurbit Genomics Database (www.icugi.org). It was also published online in the journal Nature Genetics.