Discovery of a New Self-incompatibility Allele in Apple

Abstract

A polymerase chain reaction (PCR)-based method for identifying the S -alleles in the Asian pear [ Pyrus pyrifolia (Burm) Nak.] was applied to apple ( Malus × domestica Borkh.) cultivars. With minor modifications in one of the primers, the fragments from S -genes (S-RNases) with introns were amplified from total DNA of apple cultivars possessing S2 -, S3 -, S5 -, S7 -(= Sd -), S9 -(= Sc -), Sf - and Sg -allele genotypes. S -genes within S24 -(= Sh -) and S26 -alleles were also amplified. The PCR amplification step of this method appears to be useful for preliminary investigation of apple S -genotypes, especially for species or cultivars of unknown origin or history. Using the primers, which are a part of a new S -allele, the Se -allele encoding Se-RNase with an intron in the Se -allele was amplified. We cloned the cDNA of Se-RNase, and developed a PCR-restriction fragment length polymorphism (RFLP) analysis method for Se -allele identification. S -allele genotypes of seven apple cultivars were investigated.