Genetic Analysis Of Main Fruit Traits And Construction Of The Genetic Linkage Map For Interspecific Population Of Melon

Melon(Cucumis melo L.；2n=24) is a crop of Cucumis(Cucumis), which is widely grownworldwide fruity vegetable. With the continuous improvement of living conditions,consumers increase the requirement of melon fruit quality.Therefore, research on geneticimprovement of melon fruit quality is very important. Melon fruit quality includingappearance and nutritional. Appearance quality is mainly determined by the quality of singlefruit weight, length and diameter of fruit, shape index etc. Nutritional quality is mainlydetermined by the soluble solids, total sugar, organic acid, vitamin C content etc,which areimportant factor affecting the internal fruit quality. Currently there are few studies forinheritance of melon fruit traits and using interspecific population of melon to constructegenetic map for QTL analysis.Therefore, research of inheritance of main fruit traits in melonis important：on one hand，it can be helpful to melon breeding when we have understandedthe inheritance; on the other hand，this experiment used the interspecific population of melonto constructe genetic map for locating sugar content correlated traits, which could provid thereference basis of genes location and fruit quality improvement in melon.In this experiment，we used the cultivated melon inbred line ‘0246’ and wild meloninbred line ‘Y101’ as the parents,which have significant difference in fruit traits. Sixgenerations（P1、P2、F1、F2、B1、B2）were derived from cross of ‘0246’and ‘Y101’.Thesingle fruit weight, length and diameter of fruit, fruit shape index and the fructose，glucose，sucrose and total sugar content have been measured respectively.We analyzed the inheritanceof main fruit traits and constructed genetic linkage map for locating sugar content correlatedtraits. Results are as follows:1、The single fruit weight, length and diameter of fruit, fruit shape index appeared in theF2population were multimodal distribution, showing the typical quantitative traitcharacteristics, and combination of B1, B2frequency distribution, indicating that the fourtraits controlled by major genes. The inheritance of single fruit weight, length and diameter offruit, fruit shape index were all controlled by two pairs of additive-dominant-epistatic majorgenes plus additive-dominant-epistatic polygene model effects (E-0).And the heritabilityvalues of major genes in F2population were estimated as79.20%,87.80%,74.21%and85.03%, respectively. This implied that the heritability of major genes controlling fruit mass, length of the fruit, diameter of the fruit and fruit shape index were high in F2population,with less influence by environment, so the four melon fruit traits were more suitable toconduct selection in early generation.2、The fructose，glucose，sucrose and total sugar content appeared in the F2populationwere multimodal distribution, showing the typical quantitative trait characteristics, andcombination of B1, B2frequency distribution, indicating that the four traits controlled bymajor genes. Inheritance of fructose, glucose and total sugar content were controlled by twopairs of additive-dominant-epistatic major genes plus additive-dominant-epistatic polygenemodel effects (E-0).Heritability values of major genes in F2population were estimated as90.32%,82.42%and94.66%, respectively. As for sucrose content, the inheritance model wasone pairs of additive major genes plus additive-dominant polygene model effects (D-2).andthe major gene heritability value in F2population was estimated to be83.76%. Datasuggested that the heritability values of the major genes controlling fructose, glucose, sucroseand total sugar content were high in F2population and were free from environment influence,so it would be more efficient to conduct selection in the early generation.3、We obtained65paris of polymorphism primers through506paris of melon SSRmarkers with two parents.The rate of polymorphism is13.24%.Analyzed the F2populationusing the58paris of polymorphism primers，and we developed a genetic linkage map with58SSR markers and14linkage groups, which spanning726.30cM with the average markerinterval of12.74cM.4、Using the constructed genetic linkage map, we located the sugar content correlatedtraits.Two QTLs associated with total sugar and fructose content were detected, which werenamed as Ts3.1and Fru4.1.The two QTLs distributed in3,4linkage group respectively.Theycould explain14.89%and13.02%of the total phenotypic variation, and Ts3.1was a mainQTL. The genetic effects of two loci were positive additive, which could have additioneffects on the accumulation of total sugar and fructose content, respectively.