Identification of self-incompatibility alleles (S) by PCR-RFLP in radish (Raphanus sativus L.)

From 16 inbred lines of cultivated radishes (Raphanus sativus L.), 6 S-alleles tentatively named S-201 to S-206 were identified, and their dominance relationships were examined. Among the S-alleles, S-201, S-202, S-203 and S-204 were found to be co-dominant. These 4 S-alleles showed dominance with S-205 in pollen and with S-206 in both pollen and stigma, while S205 and S206 were co-dominant. Polymerase chain reaction (PCR) was performed using the radish inbred lines randomly selected from the 6 S-allele groups. The primers were based on the highly conserved sequences of the S-locus specific glycoprotein (SLG) genes in Brassica oleracea. As a result of the PCR, a single DNA fragment of about 1.16kb was amplified as expected from the original sequence of B. oleracea. The S-allele specific pattern in the restriction fragments of the PCR products (PCR-RFLP) was confirmed for the first group of S-alleles (S-201, S-202, S-203 and S-204). However, for the second group of the S-alleles (S-205 and S-206), no pCR products were obtained. The usefulness of the PCR-RFLP in a radish breeding program is described.