| Melon(Cucumis melo L.)is a kind of annual herb which can be subjected to Cucumis Linn, Cucurbitaceae, and it is one kind of important industrial crops. Together with the rapid progressing of new molecular marker techniques, workings on construction of melon genetic linkage map on are in rapid development as well. To construct high density melon genetic map and to get saturated melon genetic map using the new molecular marker are two very important tasks in melon genetic research at present. However, we should also concern of some questions such as deficiency of marking linkage map, poor saturation, low genome cover rate, smaller quantity of QTL, not very accurate QTL locations, ect, especially few report of QTL on melon flower. For studying melon fertile flowering mechanism in molecular level, we found the SSR markers closely related with genes of fertile flower node and analyzed the QTL. These work will lay the groundwork for cloning of related genes and nurture of good melon species.In this experiment, the homozygous andromonoecy line TopMark was crossed with the homozygous gynoecious line WI998, provided by Jack E.Staub Lab, University of Wisconsin, USA. and by F1 self-pollinated single-seed descent(SSD), 171 F2S4 recombinant inbred lines(RILS)were obtained to construct the SSR genetic linkage map. Screening through 1219 pairs of primers with parents, we got 163 pairs of polymorphic primers, primers polymorphism is 13.4%. With the 163 pairs of primers'PCR results with 171 F2S4 recombinant inbred lines, we constructed the melon genetic linkage map which contains 138 SSR markers and 19 linkage groups spanning 1414.2cM with the average interval of 10.2 cM.Based on WI998×TopMark group genetic linkage map and investigations on first node of fertile flower in spring and autumn in 2010, we do the work of QTL analysis with MapQTL2.0 software and found 9 QTLs and their locations are on linkage groups 1,9,10 and 11 respectively. The LOD values of nine QTLs varied between 2.89 to 9.42. Four QTLs can explain more than 10% of phenotypic variation. Fp9.4 in the 9th linkage group can explain the highest phenotypic variation of 18.57%(2010 autumn, LOD=9.17). Both of Fp9.3 in the 9th linkage group(2010 spring 8.64%, LOD=6.44; 2010 autumn 17.99%, LOD=9.42) and Fp10.1 in the 10th linkage group(2010 spring 3.59%,LOD=2.89;2010 autumn 6.20%,LOD=3.43)were constant in the two seasons. Scanning results of additive effects shows that 8 QTLs have the negative value and have the i ncreased additive effects to lower first node of fertile flower. QTLFp9.4 in chromosome 9 was detected to have the highest additive effects value of -0.32 in 2010 spring. Only QTLFp10.1 had the positive additive effects values in both seasons, 0.20 and 0.18, and have the decreased additive effects to lower first node of fertile flower. Eight specific tight linkage markers of first node of fertile flower were found, including of the items: SSR01737,MU141991,TJ105, GCM206, MU173563, NR52, SSR04910 and MU146331, the shortest linkage span is 0.8cM between QTLFp 9.3 and GCM206, and these would be very important references for accurate anchor QTL research in the future. |
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