Comparison of the Fertility Restorer (Rfo) Introgression in Brassica napus Cultivars.

The ogu-INRA CMS pollination control system is a cytological variant of the radish- (Raphanus sativus L.) derived ogu CMS system introduced through interspecific introgression into Brassica napus L. When the radish restorer gene was introgressed into B. napus, a large unwanted piece of the R. sativus chromosome was introgressed with the Rfo restorer. High glucosinolates and poor agronomic performance are the main issues associated with the unwanted chromosome regions.  There are conflicting reports regarding the size of the Rfo fragment in B. napus, but it is estimated that at least 50cM of the Rfo locus was introgressed in the rapeseed genome. Significant effort has been directed in an attempt to shorten the restorer fragment, most using mutagenesis. It is hypothesized that multiple crosses and selection for improved agronomic performance has decreased the length of the Rfo introgression when compared to the original restorer line. Five crosses have been made using early and improved restorer lines. The parental restorer will be sequenced and compared to the progeny. Phenotypic characteristics will also be compared and discussed. This information will aid in the understanding of the evolution of the restorer fragment and its impact on the agronomic performance.