Integration between molecular and morphological markers for the exploitation of olive germoplasm (Olea europaea)

Three olive cultivars (Oliva Nera di Colletorto, Noccioluta, and a probably a new local genotype) from two strictly related areas of Molise region (south-centre of Italy) were characterized by combining molecular data (eight SSRs analyzed on leaves) and morphological features (thirty-one parameters from leaves, drupes and pits). Both molecular and morphological analyses have shown a very good separation of the three endemic cultivars. A high correlation between morphological and molecular data was found using Mantel's test. The morphological traits of pits were less influenced by environmental pressure than the leaves and drupes; therefore, the pits are more affected by genetic control and might be considered a helpful tool for cultivar characterization and identification. Potential and limitations of three statistical models computed to perform cultivar identification by morphological measures is also discussed. We demonstrated that molecular and morphological analyses are useful for distinguishing new accessions and studying local varieties to preserve genetic diversity, even at small geographical scale in such an unequivocal way; hence the methodology could be proposed as a tool to discriminate widespread cultivars, with long genetic distances.

► A high correlation between the morphological and molecular data was found.
► There is an evidence of genetic control on morphological traits of the pits.
► The leaves and drupes were more affected by environmental pressure.
► Three statistical models for cultivar identification were built.
► The synonymy between Oliva nera di Colletorto and Noccioluta cultivars was resolved.