Marker-assisted selection for two dominant powdery mildew resistance genes introgressed into a hybrid grape population

Abstract Molecular marker-assisted selection (MAS) was carried out to track the inheritance of Run1 and Ren1 , two dominant powdery mildew resistance genes that originate from different genetic resources. The Run1 locus was introgressed from a Muscadinia rotundifolia  ×  Vitis vinifera BC 4 hybrid plant derived from a recurrent pseudo-backcross breeding scheme, whereas the Ren1 locus was introgressed from the powdery mildew-resistant V. vinifera L. variety Kishmish vatkana. Introduction of the Ren1 resistance gene of V. vinifera origin into the breeding program makes possible the long-term defence of the dominant Run1 gene. Using a BC 5 (BC 4  × Kishmish vatkana) hybrid progeny consisting of 441 plants and applying several SSR and BAC-derived CB markers, we demonstrated that the powdery mildew-resistant phenotype co-segregated with the presence of at least one resistance locus-linked marker in the genome. Our data also corroborated earlier findings that the M. rotundifolia -derived Rpv1 and Run1 loci are closely linked. To further streamline the selection process, we developed a multiplex PCR- and agarose gel electrophoresis-based method for the simultaneous detection of both Run1 and Ren1 . The results illustrate that MAS offers a rapid and accurate method to select hybrid genotypes that combine multiple loci of interest in grape.