Determination of self-incompatibility genotypes of Korean apple cultivars based on S-RNase PCR

To prevent self-fertilization, apple has a gametophytic self-incompatibility mechanism, part of a widespread intraspecific system, that is controlled by a multi-allelic locus. This attribute has been exploited in breeding programs for new cultivars. Likewise, many apple orchards depend on artificial pollination. Therefore, molecular analysis and early identification of the self-incompatibility (S) genotype could greatly improve breeding schemes and pollen donors selection. Here, we PCR-amplified the S-RNase PCR fragments from a total of 14 cultivars and parents, using new primers (ASPF3+ASPR3) common to 23 S-alleles in apple. The S-genotypes were determined for the following: 'Hongro' (S1S3), `Gamhong' (S1S9), `Saenara' (S1S3), 'Chukwang' (S3S9), 'Hwahong' (S3S9), 'Seokwang' (S3S5), 'Hwarang' (S1S9), 'Sunhong' (S3S9), 'S.E.B.' (S1S19), 'S.G.D.' (S2S3), and Mollie's Delicious' (S3S7). We also confirmed the characteristics of the S-genotypes for eight Korean apple cultivars by PCR-Southern blot analysis, using seven S-RNases as probes.