Submitted to: National Watermelon Association Newsletter
Publication Type: Proceedings
Publication Acceptance Date: March 25, 2005
Publication Date: April 20, 2005
Citation: Levi, A. 2005. Wild watermelon cultivars searched for disease resistance. The Vineline: Official Bulletin of the National Watermelon Association. March/April 2005, page 66. Technical Abstract: DNA fingerprinting analysis indicated low genetic diversity among American heirloom cultivars of watermelon. Over 1,700 U.S. Plant Introduction (U.S. PIs) of watermelon (Citrullus spp.) were collected in different parts of the world and are maintained by the ‘Plant Genetic Resources and Conservation Unit’, Griffin, GA. In recent years Citrullus PIs were evaluated for resistance to powdery mildew, bacterial fruit blotch, gummy stem blight, and papaya ring spot virus. Also, different PIs were evaluated for resistance to whiteflies, spider-mites, and nematodes. A few PIs were found to contain resistance to these diseases or pests. A major objective is to incorporate the genes conferring resistance into cultivated watermelon without compromising fruit quality. In order to accomplish this objective a genetic linkage map is being constructed for watermelon using DNA markers. Also, a cDNA library representing the genes that are differentially expressed in watermelon flesh has been constructed. The cDNA library is being used for isolating genes controlling rapid cell division, and carotenoid biosynthesis in watermelon fruit. These genes might be useful and improving watermelon fruit quality in the future.