Study On Genetic Diversity And Hybrid Determination Of Melon (Cucumis Melo L.) Germplasm By Using RAPD And ISSR

Random amplified polymorphic DNA (RAPD) and Inter-simple sequence repeat (ISSR) molecular markers were used to detect the genetic diversity of melon(C玞w/w/s melo L.) germplasms, and melon hybrid were determinated by using RAPD. The result are the following:Experiment was made to investigate the amplification efficiency of different amplification conditions, Optimum combinations of amplification conditions (dNTP density, primer density, Mg2+ density, Taq DNA polymerase density, etc.) were identified rapidly and effectively. Time-saving reaction procedures for RAPD-PCR and ISSR-PCR were determined through experiments. As a result, a satisfactory RAPD and ISSR techique systems for melon (Cucumis melo L.) with desirable repeatability and resolution was estblished.A total of 21 RAPD primers and 10 ISSR primers (ISSR-10 primers is evenly composed of ISSR-2 and ISSR-4) were identified with polymorphism among the entries. For RAPD markers, 106 polymorphic bands were produced, percentage of polymorphic bands (PPB) was 58.62%, mean polymorphism information content (PIC) was 0.47. For ISSR markers,73 polymorphic bands were generated, PPB was 65.51%, mean PIC was 0.53. UPGMA cluster analysis based on two molecular markers data divided these melons into two groups: wild melon group and cultivated melon group. The distance of each wild melon germplasms are far, cultivated melon group was classified into two sub-groups, which are thick-peel melon and thin-peel melon. They are consistent with the grouping based on taxology systematic botany. For accession "2002-3l"(No.7), the result of cluster analysis is different based on RAPD and ISSR, maybe it was related to "2002-31" was a hybrid of thick-peel melon and thin-peel melon, and it maintained the genetic traits of its parent in course of inbreeding. According to that, there hasn't absolute bounds between thick-peel melon and thin-peel melon. In sub-groups,the different of cluster analysis between RAPD and ISSR was distinct, it showed melon variation was complicated. Genetic similarity matrices revealed that the estimates of correlation coefficients of RAPD and ISSR were significantly correlated. Based on the results, RAPD and ISSR can be applied to detectgenetic diversity analysis among melon germplasm.RAPD technique system was established to determinate quickly melon hybrid. A DNA extraction method was posed that extracted DNA quickly by bourgeoning melon seed, by comparison with CTAB, the amplified patterns hadn't distinct difference, the result indicated that the quick DNA extraction method could be applied to PCR reaction, and it was suited to hybrid identification of melon, Eight primers were picked out for genetic purity determination from eighty arbitrary primers by RAPD analysis between parent and hybrid, for ZmOl, they were OPN11, OPM17; for Zm02, they were OPA02, OPM16, OPM17; for Zm03, they were OPN06> OPN1K OPM17. The primers OPN11 could be used for purity determination in zmOl and Zm03; the primer OPM17 could be used for genetic purity determination in all these three hybrids, because male parent of Zm02 and Zm03 were the same one, the haracteristic band of Zm02 and Zm03 was OPMl 7-700.All the primers picked out amplified respectively the characteristic band of male parent in 20 hybrid individuals, the result of sampling test in field conformed to reality. It showed hybrid determination in melon by using RAPD was reliable.