Mapping and genetic characterization of loci controlling the restoration of male fertility in Ogura CMS radish

Abstract

Three Raphanus populations (BC1, F2 and R8) each segregating for the restoration of Ogura CMS were used to map restorer loci. The three restorer loci, Rf1, Rf2 and Rf3, each exhibited dominant restoring alleles and were each mutually epistatic. Rf1 was mapped to the upper region of Rs1 using data from each population. Rf2 was mapped to the middle of Rs2 using both the F2 and R8 populations. Rf3 was mapped to the upper region of Rs7 using the R8 population. The marker analysis and linkage mapping of the BC1 and F2 populations were described previously (Bett and Lydiate, 2003). Scoring at 114 marker loci in R8 population allowed a new map of the Raphanus genome to be integrated with the consensus map. The complex genetic control of the restoration of Ogura CMS in Raphanus is compared with the more simple genetic control of this trait previously described in B. napus. Markers linked to each of the three restorer loci will allow the routine generation and verification of defined restorer and maintainer lines for various combinations of defined restorer loci. Although the restoration of Ogura CMS in Raphanus probably involves additional loci, the identification of three loci and diagnostic markers for each provides a solid foundation for the development of a holistic model for the genetic control of this trait through mapping in additional populations.