Mapping Of The Genes Resistant To Downy Mildew And Study On The Physiological Mechanism Of The Responses Resistant To Powdery Mildew In Cucumber Inbred Line IL51 With Disease Resistance

Downy and powdery mildew are major diseases in the process of cucumber production,and the breeding of resistant cucumber is one of the effective ways to deal with the diseases.In our laboratory IL51,a cucumber inbred line with high-resistance to downy and powdery mildew,was isolated for studies on the mechanism of cucumber resistant to diseases.This study includes the mapping of resistant genes to downy mildew and the resistant mechanism of physiological responses to powdery mildew.The results are as follows:1.Mapping of the cucumber genes resistant to downy mildew:The results showed that IL51 was resistant,IL53 susceptible and F₁ susceptible.So the resistance of IL51 to downy mildew was controlled by recessive genes.Bulked segregant analysis combined with genome resequencing was used for mapping the genes resistant to downy mildew in the F₂ population derived from a cross between the IL51 and IL53.The association analysis of the single nucleotide polymorphisms?SNPs?and In Dels between the resistant and susceptible pools indicated that five possible resistant genes were mapped on chromosome 4,5,6,7,two on chromosome 4 and each on chromosome 5,6,7,respectively.Forty-nine InDel markers distributed on 7 chromosomes were designed for confirmation by PCR.The results indicated that the accuracy rate was 77.78%.These markers could be next used for mapping resistant genes.2.The data showed that the resistant physiological indexes such as the contents of O2^-,H₂O₂,SOD,POD,CAT,soluble sugar,reducing sugar,were much better in IL51 than that in IL53.