Molecular mapping of a fertility restorer gene for Owen cytoplasmic male sterility in sugar beet

We report here the molecular mapping of a fertility restorer gene (named Rf1) for Owen cytoplasmic male sterility in sugar beet. Eight AFLP and two RAPD markers, tightly linked to the Rf1 locus, were identified using bulked segregant analysis. Three AFLP markers, mAFEM972, mAFEM976 and mAFEM985, were found to co-segregate with the Rf1 allele in our mapping populations. With the help of RFLP markers, previously mapped on the sugar beet genome, we showed that Rf1 is positioned in the terminal region of linkage group Kiel III/Koeln IV. This map location agrees well with that found for the restorer gene X, which suggests that the Rf1 locus corresponds to the X locus. The availability of the molecular markers will facilitate the selection of maintainer-pollinator lines in breeding program and provide the foundation for map-based cloning of the Rf1 gene.