Location: Vegetable ResearchTitle: The Genome of Watermelon (Citrullus lanatus) Author
Submitted to: Nature Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2012
Publication Date: 11/29/2012
Citation: Guo, S., Zhang, J., Salse, J., Ren, Y., Wang, Z., Sun, H., Min, J., Zhang, H., Lucas, W., Murat, F., Zhao, H., Levi, A., Zhang, X., Wang, J., Li, Y., Fei, Z., Xu, Y., Giovanoni, J.L. 2012. The Genome of Watermelon (Citrullus lanatus). Nature Genetics. 45:51-58. Interpretive Summary: Watermelon is an important crop in the United States and throughout the world. In 2010, the total production of this nutritious fruit in the United States reached 1.9 million tons. Seed companies expend great efforts to develop high-quality seedless watermelon cultivars that produce high yields and have high nutritional value suitable for consumer needs. To accomplish these objectives, plant breeders and researchers need to identify the genes that control these important qualities in watermelon. High-throughput DNA sequencing technologies have been developed in recent years and these have facilitated expeditious sequencing of the genomes of many crop plants. However, to date, there are only a limited number of studies focused on the genome and genes of watermelon. In this research, scientists at the USDA, ARS, U.S. Vegetable Laboratory (Charleston, SC), the Boyce Thompson Institute (Ithaca, NY), and the University of California (Davis, California), have collaborated with scientists in China and Europe on sequencing and assembling the genome of watermelon. These scientists were able to sequence and assemble almost all of the watermelon genome. The DNA sequence data produced in this study facilitated the identification of a number of genes that confer disease resistance and genes that control watermelon fruit quality. These data should prove useful to plant breeders and researchers in the development of high-quality watermelon cultivars.
Technical Abstract: Watermelon, Citrullus lanatus var. lanatus, is an economically important cucurbit crop. Here, we report a high quality draft genome sequence for watermelon C. lanatus developed with the next-generation sequencing technology. The assembled genome sequences cover 83% of the estimated 425 Mb watermelon genome. Over 93% of the assembled genome sequences could be anchored to 11 watermelon chromosomes. Approximately 45% of the assembled genome corresponded to repeat sequences that commonly consist of long terminal repeat transposable elements (30%). Gene prediction identified about 23,440 protein coding genes. Shared paleopolyploidization events were characterized to elucidate the Cucurbitaceae genome paleohistory. An evolutionary scenario is presented for the origin of the 11 watermelon chromosomes, possibly derived from a 7-chromosome paleo-hexaploid eudicot ancestor. Genomic and transcriptomic analyses identified genes associated with valuable fruit quality traits, including rapid cell and fruit expansion, sugar accumulation, and carotenoid and amino acid metabolism.