Submitted to: Progress in Cucurbit Genetics and Breeding Research
Publication Type: Proceedings
Publication Acceptance Date: 3/15/2004
Publication Date: 7/19/2004
Citation: Levi, A., Thomas, C.E., Thies, J.A., Simmons, A.M., Xu, Y., Zhang, X., Davis, A.R. 2004. Developing genetic linkage map for watermelon: polymorphism segregation and distribution of markers. Progress in Cucurbit Genetics and Breeding Research. A. Lebeda and H.S. Paris (Eds.). p. 515-523.
Technical Abstract: A composite watermelon genetic linkage map is being constructed based on a testcross population and an F2 population. About 51.0% and 31.8% of the markers in the testcross and F2 populations are skewed form the expected segregation ratios. AFLP markers appeared to be clustered on linkage regions, while ISSR and RAPD markers are dispersed along the genome. AFLP markers also have greater genetic distances as compared with ISSR and RAPD markers, resulting in significant increase of map distance. An initial genetic map (based on the testcross population) that contains 27 ISSR and 141 RAPD markers has a total linkage distance of 1,166.2 cM. The addition of 2 ISSR, 8 RAPD and 77 AFLP markers increased the genetic distance of the map to 2,509.9 cM. Similar results with AFLP markers were also shown in mapping experiments with an F2S7 recombinant inbred line (RIL) population that was recently constructed for watermelon. Although the skewed segregation, marker order appeared to be consistent in linkage groups of the testcross and the F2 population. Experiments with SSR, SCAR, EST and RFLP markers are being conducted to saturate the linkage map of watermelon.