Mitochondrial orf463 causing male sterility in radish is possessed by cultivars belonging to the ‘Niger’ group

In addition to Ogura cytoplasmic male sterility (CMS), which is used worldwide in radish and Brassica crops, another type of CMS was found and named DCGMS. A mitochondrial candidate gene (orf463) of DCGMS was identified, but the distribution of this gene in radish species has not been clarified to date. We found that orf463 is distributed specifically in black radish cultivars belonging to the ‘Niger’ group and a line of wild species, Raphanus raphanistrum. The progeny tests using the cultivars having orf463 as a female parent demonstrated that the cytoplasm induces male sterility in radishes. Although the DNA sequences of orf463 possessed by the ‘Niger’ group cultivars are identical to those of DCGMS, the orf463 sequence of the wild radish line contained nine nucleotide substitutions, seven of which were nonsynonymous. All radishes with orf463 had both DCGMS-type and ‘Black radish’- type mitochondrial structures according to multiplex PCR. Based on these results, the mechanism of rearrangement between the two mitochondrial types was studied.