Study On Genetic Diversity Of Different Cultivars (Lines) Of Melon (Cucumis Melon L) By Using RAPD Marker

The genetic diversity of twenty-two melon germplasm resources were studied with the methods of morphological marks,isozyme marks and molecular marks. The results showed: The botanical and biological characters of twenty two melon germplasm resources were me –asured with morphological marks,the germplasm resources were classified into four groups with the method of normalization of standard derivation by statistic software of SPSS.The cluster -ing map of the relationship of the species and hybrids was drafted.The map was showed thick-peel melon could not be clustered to one class. POD isoenzymes of twenty two cultivars (Lines) were analyzed by techniques of polyacrylamide gel electrophoresis(PAGE).12 iso-POD bands were found in the zymogram and 10 polymorphic bands were produced, percentage of polymorphic bands was 83.33%.The zymogram of POD isoenzymes had significant difference between thick-peel melon and thin-peel melon,and more significant difference among hybrids of F1 and var.cassaba(Pang.)Greb of thick-peel melon,but the zymogram of POD isoenzymes had not significant difference between hetaomi and tiedanzi,and difference among var.cantalupa(Pang.)Greb of thick-peel melon too.This result indicates that the relationship is nearer to each other.The hybrids of F1 were not only homology in enzyme band from parental pair,but also different in intercross enzyme bands that parental pair hadn't,becauce of producing recombined of gene from parental pair.These could be used as an index for distinguishing between real and false hybrid. Methods for DNA extract in this study were SDS and CTAB with maturing melon cotyledon , OD20/280 value of extracted DNA was 1.6~1.7 or 1.1~2.0 by UV spectrophotometer testing. The extracted DNA were better by using CTAB than SDS.The productivity and purity of extracted DNA matched well for the requirement of RAPD-PCR. Experiment was made to investigate the amplification efficiency of different amplification conditions.Optimum combinations amplification conditions(dNTP density,primer density,Mg2+ density,Taq DNA polymerase density ect.) were identified rapidly and effectively. Time-saving reaction proedure for RAPD-PCR was determined through experiments. As a result, a satisfactory RAPD techique system for melon (Cucumis melo L.) with desirable repeatability and resolution was established. Twenty-two primers amplified 189 DNA fragments which hailed from 22 melon cultivars (Lines), 143 polymorphic bands were produced, percentage of polymorphic bands was 75.66.every primer amplified an average of 8.6 fragments, molecular weigh of bands ranged from 200 to 3000bp. The result of cluster analysis indicated that twenty-two melon cultivars were classified into two groups: thick melon group and thin melon group. The relationship of both melon groups were far,and thick melon group was classified into two groups,which were cupi melon sub-group and the others. The result of cluster analysis was near to theory. Three primers were picked out for genetic purity determination by RAPD analysis between parents and hybrid.for 19 hybrids, they were S61 S136 and S154;but for 18 hybrid, it was only S154.