Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: March 7, 2006
Publication Date: March 8, 2006
Citation: Hu, J. 2006. Improvement of an existing sunflower SSR linkage map by addition of TRAP markers derived from conserved Arabisopsis-type telomere sequences. 28th Sunflower Research Workshop, January 11-12, 2006, Fargo, ND. Available: http://www.sunflowernsa.com/research/research-workshop/documents/Hu_TRAP_06.pdf Interpretive Summary: Most of the published sunflower linkage maps had 17 linkage groups, each corresponding to one chromosome in sunflower genome. Each chromosome has two terminal ends called telomeres. Although the number of chromosomes varies with species, the sequence of the telomeres is conserved across almost all angiosperm species. In the densest sunflower linkage map, none of the telomeres has been mapped. This paper reports the application of the target region amplification polymorphism (TRAP) marker technique to map sunflower telomeres. Telomere-associated TRAP markers are generated using primers derived from the conserved Arabidopsis-type telomere sequences and a set of 92 recombinant inbred lines which had been extensively mapped with SSR markers. The added 183 markers to the previously established 17 linkage groups of the public sunflower linkage map increased marker density and deified 21 of the 34 telomeres. The markers are also potentially useful in tagging important genes located near the telomeres.
Technical Abstract: To improve an existing sunflower linkage map, we used the TRAP (target region amplification polymorphism) marker technique and the fixed primers designed against the conserved Arabidopsis-type telomere sequence repeat (TTTAGGG) to generate markers targeting the telomeres. A total of 226 TRAP markers were amplified from the DNA samples prepared from the two parental lines and 92 RILs recombinant inbred lines) at the F7 generation descended from the cross RHA280 x RHA801. This population had been used in the construction of the densest sunflower linkage map of 577 simple sequence repeat (SSR) markers. One hundred and eighty-three markers were added to the previously established 17 linkage groups by the computer program, Mapmaker. Thirty-two markers were mapped to the outermost positions of the linkage groups, defining 21 of the 34 linkage group ends of the sunflower linkage map. The rest of the added markers spread across the genome. The resulted telomere sequence-derived TRAP markers integrated very well with the mapped SSR markers. The total number of mapped markers increased from 577 to 760 and the total length of the map increased from 1424 cM to 1747 cM. The telomere sequence-derived markers mapped to linkage group ends provide an accurate assessment of the completeness of a linkage group. The markers are also potentially useful in tagging important genes located near the telomeres.