1 Key Laboratory of Biology and Genetic Improvement of Horticultural Crops（Northeast Region），Ministry of Agriculture，Harbin 150030，Heilongjiang，China；2 Horticulture and Landscape Architecture College of Northeast Agricultural University，Harbin 150030，Heilongjiang，China；3 Hainan Base of Heilongjiang Academy of Agricultural Sciences，Sanya 572000，Hainan，China
BC1P2 and F2 generations were constructed by crossing a melon inbred line‘ MR-1’ highly resistant to powdery mildew（Podosphaera xanthii）as female parent，and a melon inbred line‘ Top Mark’ highly susceptible to powdery mildew as male parent. The race of P. xanthii was identified as race 1 according to the infecting action of 13 international differential hosts for melon powdery mildew，and the resistance to powdery mildew was controlled by a single dominant gene based on the population genetic analysis of BC1P2 and F2. Through evaluating the resistance in 266 individuals of F2，the genotype analysis using cleaved amplified polymorphic sequences（CAPS），and quantitative trait loci（QTL）analysis using composite interval mapping method
（CIM）for locating the locus resistant to powdery mildew，a genetic linkage map of melon contained 203 CAPS was constructed. One QTL named PXR was detected on chromosome 12 between the 2 CAPS markers，M12-GH and M12-TE，which were tightly linked to the gene resistant to powdery mildew with the genetic distances of 0.63 cM and 0.42 cM，respectively. Sixty putative genes were located in the region with the length of 303 kb between the 2 flanking markers. Ten of them with non-synonymous single nucleotide polymorphism（nsSNP） were further identified as candidate genes resistant to powdery mildew in melon. The results suggested that 4 genes （MELO3C002434，MELO3C002437，MELO3C002441，and MELO3C002457）showed bigger differences in expression of disease resistance and susceptible might be the candidate genes resistant to powdery mildew in melon.
