Genetics Analysis and Identification of SSR Makers Linked to Downy Mildew Resistance Through BSA in Cucumber ( <scp> <i>Cucumis sativus</i> </scp> L.)

ABSTRACT The research was carried out to divulge the genetics of inheritance, nature of gene action, correspondingly to identify the SSR markers linked to downy mildew resistance in cucumber. The parents Swarna Agethi and IIHR‐438 were used and developed six generations (P 1 , P 2 , F 1 , F 2 , BC 1 and BC 2 ), the parents, filial generations and backcross populations were deployed for genetic studies. The Mendelian segregation suggested that the downy mildew resistance was governed by two pairs of recessive genes with inhibitory recessive epistasis (3 resistant: 13 susceptible) gene interaction. IIHR‐438 possessed a higher degree of resistance; and epistatic interaction (additive × dominance) was of greater importance than the main effect. Bulk segregant analysis (BSA) aided in identifying the two SSR markers (SSR 3–5 and SSR 4–13), which had polymorphism between resistant and susceptible bulk, and the markers among backcross population segregated in an equal (1:1) ratio. Genetic distance between identified markers was found to be 16.6 cM from the QTL IciMapping V3.2 software, which depicted two new quantitative trait loci (QTLs) on chromosome number 3. These findings on genetics of downy mildew resistance provide an implication to advance the reciprocal recurrent selection followed by pedigree selection to aid in the development of resistant varieties in cucumber.