Assessment of clonal genetic variability in Olea europaea L. ‘Cobrançosa’ by molecular markers

Olive tree is mainly vegetatively propagated; therefore a small level of polymorphism is expected among clones of the same cultivar. In order to access the level of intra-varietal genetic variability within a collection of 120 clones of the Portuguese olive ‘Cobrançosa’ DNA fingerprinting was performed. Ten random amplified polymorphism DNA (RAPD) primers amplified 150 fragments, of which 75 were polymorphic, while 10 inter-simple sequence repeats (ISSR) primers amplified 179 fragments of which 98 were polymorphic. ‘Cobrançosa’ clones were compared and analysed using Jaccard's coefficient with unweighted pair group mathematical averages, using the RAPD data, the ISSR data and both markers simultaneously. The data indicates a wide intra-varietal genetic variability among the clones. It was possible to cluster some clones according to geographical provenance. Analysis of molecular variance revealed greater variation within clones than among different geographical origins. Significant genetic diversity among the ‘Cobrançosa’ olive cultivar, even though the clones came from a limited geographical area, was also detected.