Title : Gene exploring of downy mildew resistance from a Cucumis hystrix introgression line of cucumber (C. sativus L.)
Downy mildew is a major devastating disease of cucumber, causing significant economic losses of yield in up to 80 countries yearly. In previous study, an introgression line derived from interspecific hybridization between cucumber and the wild relative species cucumis hystrix Chakr. (2n = 24), IL52, was selected as highly resistant to downy mildew and has been used for genetic analysis of DM resistance. Here, with an objective of identifying candidate genomic regions and candidate genes responsible for downy mildew resistance, traditional QTL mapping and BSA-seq were performed with RIL populations from the same cross changchunmici × IL52. Through a combination of QTL-seq and conventional QTL mapping, a reliable major QTL dm5.2 was identified for downy mildew resistance in cucumber. QTL-seq approach identified 9 SNPs affected 9 candidate genes associated with downy mildew resistance in cucumber. Validation and identification of candidate genes for downy mildew resistance is underway.