Integration of Korean S haplotypes controlling self-incompatibility into the unified nomenclature in radish (Raphanus sativus L.)

Self-incompatibility in radish (Raphanus sativus L.) is controlled by the S haplotype consisting of three tightly linked genes: SRK, SCR/SP11, and SLG. Since many radish S haplotypes have been reported with different nomenclature by several research groups, such discrepancy has resulted in confusion. To integrate S haplotypes identified in previous studies of Korean radish breeding lines into a unified nomenclature system, the nucleotide sequences of SRK and SLG genes isolated by different research groups were compared with each other. Two radish accessions whose draft whole-genome sequences were previously reported were shown to harbour class II RsS-9 and class I RsS-19 haplotypes, respectively. Nucleotide sequences of SLG and S domains of SRK genes were obtained from diverse breeding lines using four degenerate and 13 haplotype-specific primer pairs. A total of 27 out of 31 S haplotypes isolated in our previous study showed that SRK and SLG sequences were almost identical to those reported by other research groups. In addition, eight novel putative SRK or SLG sequences showing high homology with other SRK genes were identified. Finally, 27 S haplotypes were successfully integrated into the unified nomenclature, and the four S haplotypes containing unique sequences were renamed following the unified nomenclature.