Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/8/2001
Publication Date: 8/6/2002
Citation: Levi, A., Xingping, Z., Thomas, C.E., Joobeur, T., Carle, B., Wehner, T.C. 2002. An initial genetic linkage map for watermelon based on randomly amplified polymorphic dna (rapd) markers. Journal of Theoretical and Applied Genetics. Journal of the American Society of Horticultural Science. 126:730-737. Interpretive Summary: Watermelon accounts for 2% of the area devoted to vegetable production throughout the world. In the U.S. watermelon production has been increasing from 1.2 M tons in 1980 to 2.1 M tons in 1998, with an at the farm value of $287 million. This important crop is susceptible to a large number of diseases and pests that cause significant damage. Therefore, there is an urgent need to find genes that make watermelon resistant to diseases and pests. The cultivated watermelon is related to a wild species called Citrullus lanatus var. citroides, which is found in Africa and is an essential source of genes that can give the cultivated watermelon more resistance to diseases and pests. In order to locate these genes ARS and university scientists constructed a DNA map for watermelon using special molecular (DNA) procedures. This map will be used in genetic studies of watermelon, enabling plant breeders and scientists to find and manipulate the genes that are needed to improve cultivated watermelon varieties.
Technical Abstract: An initial genetic linkage (RAPD-based) map has been constructed for watermelon using a BC1 population [U.S. Plant Introduction accession 296341-FR (Fusarium resistant) x New Hampshire Midget] x New Hampshire Midget. The map contains 155 RAPD markers that segregate in 17 linkage groups and cover a genetic linkage distance of 1265.8 cM. Among these RAPD markers is Operon-P-01 (700 bp) that was reported as linked (3 cM) to race 1 Fusarium wilt resistance in watermelon. Each of the large linkage groups contains segments with low levels of recombination among markers (0-2.6 cM) indicating that the watermelon genome may contain large conserved chromosomal regions. BC1-F2 families are being generated and will be used to identify markers closely linked to genes that control fruit quality and Fusarium wilt (races 1 and 2) resistance in watermelon.