Powdery Mildew Resistant Genetic Analysis And Preliminary Positioning Of Resistance Gene In Cucurbita Pepo L.

Powdery mildew?PM?is a kind of fungal diseases,occurs widely throughout all over the world.It has some characteristics such as strong epidemic,frequent infecting plants,shorter latent period and drought-resistant.Powdery mildew infection can cause great economic losses and reduce the squash?Cucurbita pepo L.?yield.Chemical agents are always used to prevent the powdery mildew for the controlling methods.But it results in pollution to the environment,and the cost is also high.The chemical controlling will affect the quality of squash,and the food security is relatively down.Thus,it is important to select the squash with resistance gene.In the present study,inbred lines BS6 and BS11,which were resistant and susceptible to powdery mildew in C.pepo L.respectively,were used to construct genetic groups?F₁,F₂,BC1P1,BC1P2?for inheritance analysis and gene mapping of Pm-1 by inoculating with the disease,observing the incidence of plants,analyzing the resistance of powdery mildew and clearing the genetic development of the powdery mildew.And the resistant genetic mapping was down.The results are as follows:?1?According to the results of the identification for powdery mildew,F₁ of BS6 × BS11 and BC1P1 population were all resistant,and the segregation ratios of the resistant plants and susceptible plants in the F₂ population and BC1P2 population fitted the 3:1and 1:1 respectively.Therefore,genetic analysis showed that the resistance to powdery mildew was controlled by a pair of dominant genes.The pair of genes was named Pm-1.?2?Of the 743 pairs of the SSR primers tested,there were 68 pairs of primers were exhibited distinct polymorphisms between the parental lines BS6 and BS11.Of 68 pairs,5 pairs of SSR markers were related to resistant gene for powdery mildew in the resistant and susceptible pools through BSA method.?3?Depending on the disease-resistant identification results of F₂ population and analyzing the five pairs of SSR markers for resistance to powdery mildew,the resistance gene?Pm-1?for powdery mildew was taken to position.And the positioning region for resistance gene?Pm-1?was confirmed.The two pairs of primers,SSR14 and SSR237,were the linked markers to the resistance gene.the resistance gene?Pm-1?was positioned between SSR14 and SSR237,and the genetic distance were 8.7 and 5.2cM between SSR14 and SSR237.?4?For further verification of the genetic positioning result,BC1P2 population?F₁×BS6?was taken as the experimental material,the SSR237 markers was applied in the experiment for the genetic analysis.The result showed that the genotype identification of the SSR237 primer was consistent with the phenotype result of the resistant plants.It also further demonstrated that SSR237 primer was linked closely to the resistance gene and it can be used to breed with maker-assisted selection.