Review of November 25 2012, Nature Genetics Article, "The draft genome of watermelon (Citrullus lanatus)" 'and resequencing of 20 diverse accessions"Edit
In the recent edition of Nature Genetics a paper was submitted describing the genome of the Chinese Watermelon. Watermelons are one of the top five consumed fruits worldwide with an annual harvest reaching 90 million tons. They are considered to be a cucurbit crop (relative of gourd vegetables) with the family Cucurbitaceae, the genus Citrullus, and the species lanatus. Additionally, watermelon (C. lanatus) have 3 subspecies: C. lanatus lanatus (resembles ancient watermelon, 'tsamma', 'citron' watermelons), C. lanatus mucosospermus (large edible seeds, 'egusi' watermelon), and C. lanatus vulgaris (sweet desert watermelon, linked to modern cultivated watermelons) all of which are thought to have orginated in South Africa.
After many years of cultivating watermelon, the diversity in the genome is thought to have narrowed despite the varieties presently available. This study evaluated the diploid watermelon, native to East Asia with the hope of gaining biological insight and evalutating the potential for crop improvement.
Initially researchers estimated the genome size of the Chinese watermelon to be 425 Mb. The acquistion of 46.18 Gb of genomic sequence, implied 108.6 coverage of the total genome. However, de novo assembly of the genomic sequence only represented 83.2% of the total genome at 353.5 Mb. The remaining 16.8% of the genome (the unassembled reads) were aligned to the assembled DNA using less stringent criteria. Ultimately, the unassembled sequences were comparable to regions within the assembled genome and resembled transposable element arrangement.Conclusions from genome sequencing are that there are 353.3 Mb in 11 chromosomes in the Chinese watermelon.