Allelic discrimination of the Restorer-of-fertility gene and its inheritance in peppers (Capsicum annuum L.)

Cytoplasmic male sterility (CMS), one of the most important traits in crop breeding, is used for commercial F-1-hybrid seed production in peppers (Capsicum annuum L.). A nuclear gene, Restorer-of-fertility (Rf), can induce normal pollen production in CMS plants resulting in fertility. Since the first report of fertility restoration in peppers, various inheritance modes have been suggested, including the presence of a third haplotype of the locus. The pepper Rf gene has not been cloned, and calculated genetic distances of linked markers have varied between research groups. A more precise allelic test and additional genetic mapping are needed to accurately select recombinants for use in marker-assisted backcrossing (MAB). Therefore, the reliability and application of these markers for allelic selection of the Rf gene was tested. Two different F-2 populations, Buja and Tamna, were used for the construction of a linkage map. From these linkage groups, a new closely linked flanking marker of the Rf gene were identified. Previous allelic testing revealed the existence of a third haplotype, Rfls (7701) , which can function as dominant (Rf) or recessive (rf). In a previous report, Rfls (7701) was considered to be linked to unstable male sterility (MS). However, our results suggest that unstable MS was induced by a gene residing at another locus rather than by Rfls (7701) haplotype-linked allele.