Molecular diversity and genetic relationships of southern Italian olive cultivars depicted by AFLP and morphological traits.

Knowledge of the molecular and morphological diversity of olive cultivars is an essential pre-requisite for cultivar identification and is of considerable economic importance for the production of olive oil with Protected Denomination of Origin (PDO) status. In addition, studies on the genetic diversity of olive trees are valuable for germplasm conservation. Here we report on amplified fragment length polymorphism (AFLP) profiling of olive genotypes that represent varieties used mainly for the production of PDO olive oil in the Campania region of Italy. AFLP analysis of 70 genotypes provided clear genetic differentiation between cultivars. Furthermore, DNA-profiling revealed synonyms and homonyms, indicating that erroneous denominations occur more frequently among local germplasm than in common varieties. Genetic distances were also calculated on the basis of 40 phenotypic traits, including morphological characters recommended for distinctness, homogeneity, and stability testing. Morphological and AFLP-based genetic distances yielded different hierarchical patterns, although the two data-sets were both useful for assessing the presence of genetic variation.