Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/18/2003
Publication Date: 3/25/2004
Citation: Zhang, R., Xu, Y., Yi, K., Zhang, H., Lie, L., Gong, G., Levi, A. 2004. Genetic linkage map for watermelon derived from recombinant inbred lines (rils). Journal American Society Horticultural Science 129:237-243. Interpretive Summary: Watermelon is an important crop, and accounts for 2% of the world area devoted to the production of vegetable crops. Many diseases and pests cause Significant damage to watermelon fields all over the world, and there is great need to develop resistant varieties. To effectively use resistance genes plant breeders and geneticists need genetic (DNA) maps that show the location of genes on chromosomes. In this study, Chinese and American researchers developed a genetic map for watermelon, and a DNA marker that shows the location of a gene conferring resistance to Fusarium wilt was found. Fusarium wilt is a major disease of watermelon worldwide. The genetic map and the DNA marker can be used in breeding programs designed to develop watermelon varieties resistant to Fusarium wilt disease. Also, the genetic map should prove useful in future efforts to determine the chromosome location of other important watermelon genes.
Technical Abstract: A genetic linkage map was constructed for watermelon using 117 recombinant F8 inbred lines (RILs) descended from a cross between the high quality inbred line 97103 (C. lanatus var. lanatus) and the Fusarium wilt (races 0, 1 and 2) resistant U.S. Plant Introduction (PI) 296341 (C. lanatus var. citroides). The linkage map contains 87 randomly amplified polymorphic DNA (RAPD) markers, 13 inter simple sequence repeat (ISSR) markers, and 4 sequenced characterized amplified region (SCAR) markers. The map consists of 15 linkage groups. Among them a large linkage group of 31 markers covering a mapping distance of 277.5 cM, six large groups each with 4-12 markers covering a mapping distance of 51.7-172.2 cM, and eight small groups each with 2-5 markers covering a mapping distance of 7.9-46.4 cM. The map covers a total distance of 1,027.5 cM with an average distance of 11.54 cM between two markers. The map is useful for the further development of quantitative trait loci (QTLs) affecting fruit qualities and for identification of genes conferring resistance to Fusarium wilt. The present map can be used for further construction of a reference linkage map for watermelon based on an immortalized mapping population with progenies homozygous for most gene loci.