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

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 BC4 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 BC5 (BC4 × 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

Mapping of easy to screen SSR markers for selection of RFLP markers-bracketed downy mildew resistance QTLs in pearl millet

Pearl millet (Pennisetum glaucum L.), the sixth most important food-grain crop, is a highly nutritious and multipurpose cereal which can grow in the poorest soil. The crop suffers from substantial annual yield losses due to devastating downy mildew (DM) disease caused by fungus Sclerospora graminicola. Using a F2 population derived from the cross of H 77/833-2 and ICMP 451, linkage groups 1 and 4 have been reported to carry QTLs for resistance to Sclerospora graminicola. These QTLs were bracketed with labour intensive restriction fragment length polymorphism markers thus hampering their use in marker assisted selection (MAS). The current study reports saturation of DM resistance QTL regions with easy to screen simple sequence repeats markers which can be efficiently utilized in MAS programmes for improving the elite cultivars of pearl millet against this disease.Peer reviewe