Analysis Of Genetic Diversity In Crisp Melon(Cucumis Melo Var.conomon Group)Germplasm Resource

Crisp Melon?Cucumis melo var.conomon Group?is a variety of Cucurbitaceae melon species,rich variety,different traits,with a unique"crisp"flavor.Crisp Melon mainly concentrated in the Jiang-huai Plain,a small amount distributed in other areas.In order to clarify the genetic relationship between the varieties,it is necessary to classify and analyze the molecular resources of the melon germplasm resources.In this study,104 germplasm samples were collected from the Yangtze River and Huaihe River Basin,and 104 clonal melon germplasm were analyzed by RAPD,ISSR and SSR to identify the genetic relationship among germplasm.The main findings are as follows:?1?The genomic DNA of melon was extracted by modified CTAB method,and the RAPD-PCR reaction system was established in the reaction system.In the 25?L reaction system,the primers contained 0.8?mol/L,dNTPs 0.3?mol/L,Taq DNA polymerase 1 U,Mg²⁺0.5 mmol/L,DNA template 30 ng.In the 20?L reaction system,the reaction medium contained 0.2?mol/L of primers,0.3 mmol/L of dNTPs,1.2 U of Taq DNA polymerase,Mg²⁺1.0 mmol/L,70 ng of DNA template,10×Buffer 2.0?L.SSR-PCR reaction system:In the 20?L reaction system,containing the primer 0.4?mol/L,dNTPs 0.2 mmol/L,Taq DNA polymerase 0.5 U,Mg²⁺1.0 mmol/L,DNA template 30 ng,10×Buffer 2.0?L.The system laid the foundation for the analysis and evaluation of genetic diversity of melon germplasm resources.?2?Among the 98 primers,33 polymorphic primers were screened according to their polymorphism ratio,85 polymorphic loci were detected in 17 RAPD primers,50were detected by 10 ISSR primers polymorphism loci,and 60 polymorphic loci were detected in 6 SSR primers.A total of 195 polymorphic loci were used for genetic evaluation.Among them,the highest GD?0.9826?,ISSR823?0.2933?,the average was 0.6583.The PIC values of the 33 primers were 28.67%?RAPD18?to 98.23%?SSR08?,with an average of 63.12%.Of the 33 markers,15 were highly efficient.?3?A total of 104 melon germplasm were collected and divided into five main groups by cluster analysis.And the Group I and Group II each include only one variety,respectivly H14 and H29;Group III group contains fivevarieties?H11,H13,S8,S13,S39?;Group V group contains F1-7 and F2013,GF,H39 and S48 a total of 11varieties;the remaining 86 copies of the composition of the IV group,representing a wide range from the Yangtze River Basin.The minimum genetic distance between S26 and S27 is 0.2121,indicating that they are the most similar germplasm,followed by 0.2424 between F1 and F2,and H14 and H7,H38,S29,S30,S46 are genetically least similar,the genetic distance was 0.9697.