| Watermelon is a worldwide horticulture crop. It plays an important role in the economy of agriculture of our country. In this study, a RI population which is obtained by hybridizing watermelon cultivar 97103 which possesses high soluble solids content, thin rind and susceptible to Fusarium wilt with the wild species PI296341 which has low soluble solids content, thick rind and resistant to Fusarium wilt was used to construct RAPD and SCAR, SSR and ISSR, AFLP molecular genetic map respectively. On the base of integrated map, several main agronomic traits of watermelon were located in the map. The main results were as follows:(1) The first RI population in the world was constructed. It uses watermelon cultivar 97103 and wild species PI296341 as parents, their FI progeny selfcross continuously for eight times. At present the population has been shared with several labs in America.(2) Selecting 66 RAPD primers out of 600. Among the 66 primers, 5 RAPD primer to SCAR primer were successfully transformed to SCAR primers. With their segregation and distribution in RI population, a RAPD and SCAR genetic map, which contains 94 RAPD marker loci and 5 SCAR marker loci was build up. This map consists of 14 linkage groups covering 806.7 cM with an average distance of 8.2 cM between locus.(3) One set of stable SSR reaction system was established. This system include: IxPCR buffer, 2.0mMMgCl2, 200uMdNTP, 8-10Picomole Primer Pairs, 60 ng Template DNA, 1 U TaqEo Amplification was performed by 40 cycles of 1 min at 94 C, 30 seconds at 56-68C, 1 minute at 72 C, with a 2 minutes pre-inactive of 94 C and a 5 minutes post-elongation of 72 C, and the product was stored at 4 C.(4) A SSR and ISSR molecular map with 38 SSR markers and 10 ISSR markers was constructed by selecting 13 SSR primers out of 15 and 4 ISSR primers out of 5. This map consistsof 11 linkage groups covering 558.1 cM with an average distance of 11.9 cM between locus.(5) A new modified silver staining-AFLP and infrared dye-labeled-AFLP technique system of watermelon was stablished. Using the silver staining-AFLP system, 11 EcoRI/Msel primer group out of 64 was selected. Then using the 11 primer groups and infrared dye-labeled-AFLP technique the segregation and linkage of AFLP polymorphic bands were analysed and a AFLP molecular genetic map, which contains 160 AFLP marker loci was built up. This map consists of 16 linkage groups covering 1551.3 cM with an average distance of 9.7 cM between locus. Furthermore, the selecting data of AFLP primer pairs provided an experimental base for complete AFLP map construction.(6) Together with field data, an integrated genetic map of watermelon was constructed containing 86 RAPD markers, 3 SCAR markers, 24 SSR markers, 10 ISSR markers, 79 AFLP markers, and 1 morphological markers. This map consists of 19 linkage groups, covering 1383.8 cM of the genome with an average marker interval of 6.8 cM. In this map, the bitterness gene is found to link with AG_AC 112 marker, which the distance between them is 16.0 cM.(7) On the base of integrated map, 4 fruit character of watermelon with WinQTLCart/1.2 version were analysed. 8 QTLs is identified for SSC, 1 QTL for HR, 5 QTLs for WSF and 1 QTL for WTS. In addition, the resistance against Fusarium wilt was analysed in QTLs for the first time. 8 QTLs were identified. QTL location map could be applied in marker-assisted selecting of watemelon breeding. And it also provided theoretical base for improvement of fruit characters of watermelon.
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