Genetic variability between different accessions of some common commercial olive cultivars

Leaves of 22 accessions of olive (Olea europaea L.) from three named cultivars (Manzanillo, Kalamata, and Verdale), and 17 accessions from cultivars with names that are suspected to include synonyms (Corregiola, Corregiolo, Frantoio, Frantoja, Frantojol, Nevadillo, Nevadillo Blanco, and Picual) were obtained from Israel, Italy, the USA and Australia. Their genetic variability was investigated using random amplified polymorphic DNA (RAPD). Analysis of the PCR products was achieved by using the simple matching coefficient and UPGMA clustering. 'Manzanillo' and 'Kalamata' showed a within-cultivar genetic similarity of at least 98% irrespective of source. In contrast, 'Verdale' showed a high genetic variability, with some accessions having less than 80% similarity to others. 'Picual' and 'Nevadillo' (including 'Nevadillo Blanco'), which clustered at 69%, are possibly distinct cultivars. The identity of 'Corregiola' and 'Frantoio' and their synonyms is uncertain. Considering the extent of the genetic distances involved between accessions within the 'Corregiola'/'Frantoio' group, and also within the 'Verdale' group, it is likely that some of the within-group accessions are separate cultivars.