Identification of RAPD and SCAR markers linked to a restorer gene for Ogura cytoplasmic male sterility in radish (Raphanus sativus L.) by bulked segregant analysis

DNA markers linked to a fertility restorer (Rf) gene for Ogura cytoplasmic male sterility in radish (Raphanus sativus L.) were screened by bulked segr egant analysis using random amplified polymorphic DNA-polymerase chain reac tion (RAPD-PCR) and high-resolution agarose gel electrophoresis. Ten male-f ertile and 10 male-sterile plants arbitrarily selected from the F-2 segrega ting population made by the selfing of an F-1 plant between 'MS-Gensuke' (a male-sterile line possessing Ogura cytoplasm) and 'Comet' (a restorer havi ng a nuclear Rf gene), were used as the materials for bulked DNA samples. U sing 10 out of 260 arbitrary primers tested, RAPD fragments specific to the bulked DNA samples from male-fertile F-2 plants were identified. Further l inkage analysis performed with 89 individuals in the F-2 segregating popula tion showed that the seven RAPD markers were linked to the Rf gene. RAPD ma rkers distributed on both sides of the Rf gene, and the closest marker, OPH 11(410) was positioned 1.2 cM from the Rf gene. The three closest RAPD mark ers to the Rf gene were converted to SCAR markers by molecular cloning and nucleotide sequencing. This allowed identification of more reliable DNA mar kers linked to the Rf gene than the RAPD fragments.