Development and characterization of SCAR markers associated with a dominant genic male sterility in rapeseed ( Brassica napus . L )

Rs1046AB is a dominant genic male sterility (DGMS) line in rapeseed, of which the sterility was ever regarded to be conditioned by the epistatic interaction of two individual genes, i.e. the male sterility gene (Ms) and its suppressor gene (Rf). This system not only provides a tool for assisting in recurrent selection but also a promising alternative to the cytoplasmic male sterility (CMS) and self-incompatibility (SI) systems for hybrid production. Based on previous studies, we converted two AFLP markers linked with the Ms gene into a dominant and a co-dominant SCAR marker, respectively. The putative linear order relationship of three dominant SCAR markers with the same genetic distance from the Rf gene, was also determined by an examination of whether the homologues of these markers are present or not in different lines carrying the Rf gene. Interestingly, a bigger fragment generated by the closest marker linked to the Rf gene was observed in all lines carrying recessive allele rf, suggesting this marker is a co-dominant marker. This finding was incompatible with our previous conclusion; however, it presented strong evidence that the sterility of this dominant GMS should be explained as an inheritance model of one gene with multiple alleles. These SCAR markers developed here specific for Ms and its alleles will be especially valuable in marker-assisted DGMS three-line breeding.