S-allele genotypes of nine apple (Malus xdomestica Borkh.) cultivars were i
dentified using S-allele-specific polymerase chain reaction (PCR)-restricti
on fragment-length polymorphism (RFLP) analysis. A new S-allele, Sg, was pr
oposed to be present in 'American Summer Pearmain', 'Indo', 'Kitanosachi',
and 'Meku 10'. This allele is very similar to Sf at the nucleotide sequence
(92%) and deduced amino acid sequence (94%) levels.