Genetic diversity among accessions of an ancient olive variety of Cyprus

To evaluate germplasm variability and to discriminate between accessions of 'Ladolia', an ancient olive variety of Cyprus, different accessions from a germplasm collection were screened with 11 selected oligonucleotide primers in RAPD-PCRs. A total of 49 polymorphic markers were scored, the combination of which resulted in 70 distinct electrophoretic patterns. Based on either unique or combined patterns, all accessions were identified. Seven genotype-specific markers were detected. One RAPD marker could distinguish accessions according to fruit size. Genetic similarities between accessions, estimated using the Dice similarity coefficient, indicated a high degree of genetic diversity among 'Ladolia' accessions. Genetic relationships were estimated by the unweighted pair-group method with arithmetic averaging (UPGMA) and principal components analysis (PCA). Three main groups of accessions were detected. The first group was generally composed of accessions with small-sized fruits and could be further divided into two subgroups. According to PCA, most accessions with medium- or large-sized fruits were clustered together. Our results support previous observations suggesting that 'Ladolia' is actually a highly variable mixture of genetically distinct landraces.