Construction Of Melon Chromosome Segment Substitution Lines And Genetic Location Of The Powdery Mildew Resistance Gene In Melon

Melon is one of the important horticultural crops worldwide. Xinjiang is the main producing areas of melon in C hina. Xinjiang melon has unique flavour, populared by the public. However, Xinjiang melon is also prone to be attacked by the disease, which seriously affected the yield and quality of melon, resulting in huge economic losses. Thus, the molecular marker-assisted breeding was used to construction a set of melon chromosome segment subsitiution to transfer wild melon important resistant traits into commercial melon, which is important to improve melon genetic diversity and disease resistance.In this study, wild melon "MR-1" and Xinjiang melon “Queen " were used to construction a set of substitution lines using SSR molecular marker-assisted breeding. The wild melon " MR-1 " is the donor parent, and Xinjiang melon “Queen" is recipient parent. During the process, the melon chromosome segment subsitiution lines was gained after four generations of backcrossing, which was contained the donor parent of the whole chromosome substitution fragment for the recipient parent’s genetic background. Meanwhile, we used the resistant and susceptible strains melon, and combined with the method of SSR markers, choosed the molecular markers closely linked to powdery mildew resistance genes, and mapped the powdery mildew resistance genes preliminary.The result showed that:(1) According to the genetic linkage map of BC1 plants, 89 polymorphism SSR markers between parents were used to select entire donor parental chromosome segments in BC2 population.26 BC2 individuals entire donor parental chromosome segments,contained LG I to LG Ⅻ, were picked out by using polymorphism SSR markers and marker-assisted breeding method.(2) BC3 plant was obtained by 26 BC2 individuals backcrossed with recipient parent. The obtained 368 BC3 individuals were detected by polymorphism SSR markers for selecting substitution lines. A total of 29 entire donor parental chromosome segments were selected. Thoese BC3 plants contained LG I to LG Ⅻ of donor parent.(3)bc4plantwasobtainedby29bc3individualsbackcrossedwithrecipientparent.theobtainedbc4 individualsweredetectedbypolymorphismssrmarkersforselectingsubstitutionlines.atotalof33entiredonorparentalchromosomesegmentswereselected.thoesebc4plantscontainedlgitolgⅫofdonorparent.(4)theresultshowedthattheresistancegenetopowderymildewinmelonwmr-29 strainswascontrolledbytwodominantgenes,anditwaslocatedonlgⅡ、lgⅫ,andalsofound11 markerswaslinkedtopowderymildewresistantgeneofmelon.