S-genotypes of 15 apple cultivars and self-compatibility of 'Megumi'

S-genotypes of 13 apple (Malus x domestics Borkh.) cultivars and 10 progeni es of 'Megumi' were identified by S-allele-specific PCR- RFLP analysis. The S-genotypes of 'Gala' and 'Fuji' were reconfirmed by the analysis. The S-g enotypes of 'Kinsei' (S2S9) and 'Kizashi' (S2S3), were inconsistent with ex pected S-genotypes of their parents, indicating that they are derivatives f rom some other pollen parents having S-9 - or S-3 -allele. 'Tsugaru', 'Akag i', and 'Youkou' seem to have been produced by using pollen parents possess ing S-7 -,S-7 - or S-9 -allele, respectively. The S- genotype of self- compatible 'Megumi' was identified as St Sg; no mu tation occurred within either of the S-genes. The reciprocal crosses betwee n 'Megumi' and 'Hatsuaki' (S3S9) resulted in fruits with seeds, whereas tho se between 'Megumi' and 'Redgold' (S2S9) or 'Megumi' and 'Kinsei' (S2S9) re sulted in no seeds. These results indicate that the self-compatibility of ' Megumi' is not attributable to defects within the S-genes.