Identification of S Haplotypes in Commercial F1 Hybrid Cultivars of Radish by PCR-RFLP Analysis

Self incompatibility (SI) of Cruciferous crop has been studied not only to find out the evolution of the self incompatibility system, but also to identify the S haplotypes of the plant materials on the practical breeding programs. It has been reported that SRK and SCR/SP11 are the main components of the pistil and pollen interaction on the process of SI. In addition, SLG is also related to this process and closely linked to SRK and SCR/SP11 gene. To study S haplotype variation of commercial F1 radish cultivars cultivated in Korea, SLG and SRK DNA of the 44 cultivars were analyzed with PCR-RFLP. Totally 12 S haplotypes were found from the commercial F1 cultivars. S₄ (II), S₅ (II), S₈ (I), S₁₇ (I), and S₂₁ (II) were frequently identified from over 10 cultivars. S₁₁ (I), S₁₃ (II), S₁₈ (I), S₃₀ (I), and S₃₁(I) were rarely identified among the cultivars. Although 12 different haplotypes were identified from the cultivars, 79% of cultivars have only 5 different S-alleles. The frequency of the class II S haplotype (41/77) was higher than that of class I (36/77), but the number of class I haplotype was larger than that of class II. Surprisingly, 7 of the 44 F1 hybrid cultivars have only one S-allele by this method. We could not decide whether this homozygosity of S-allele is originated from the S-allele itself of the cultivars or limitation of PCR-RFLP analysis. To confirm this homozygosity on the F1 hybrid cultivars, an additional experiment will be need with other primer sets of the SLG, SRK and SCR/SP11 DNA sequences.