Identification of S-Alleles in Several Apple Cultivar

Two Polish apple cultivars 'Ligol' and 'Odra' and two Polish apple clones 'U633' and 'U1065' were utilized for studies of self-incompatibility. PCR amplification using FTC143 and FTC144 S-allele specific primers for S-7 failed to differentiate between the S-7 and S-z alleles. Based on available sequence data, a new set of primers upstream and downstream of the hypervariable region of apple S-RNases was designed. Using the RT-PCR method, cDNA was amplified on RNA isolated from styles of selected plants. PCR products were cloned and sequenced. In cultivar 'Odra' and clones 'U633' and 'U1065', a new S-allele, showing 97% of identity with Sauc19 derived from Sorbus aucuparia (EF494758) and denoted as a S-kb, was identified. The S-z allele was associated with cultivar 'Odra', and S-7 with 'U1065'. In 'Ligol', the agronomically most important cultivar in Poland, S-2 and S-9 are present.