Genetic relationships among cultivated and wild olives revealed by AFLP markers

The cultivated and wild forms of olive represent one of the widest and well preserved genetic system among fruit crops. In fact over 2000 varieties of olive are still under cultivation and wild olives represent an important component of the Mediterranean maquis. To date the level and distribution of the entire variability, especially at molecular level, were never evaluated. The study of olive diversity could instead represent a powerful tool to monitor the presence within the wild germplasm of agronomically interesting traits, to explore strategies for the introgression of such traits into the cultivated genotypes and to understand the potentiality of new gene combinations. Our study compared wild olives coming from different sites with some widely cultivated varieties. The within and between groups variability was tested and it was possible to observe that varieties and wilds clustered separately. Two types of wild olives were recognized: one showing a higher relatedness with the cultivars and a second one with a molecular profile clearly different from both cultivated and other wild plants. The samples coming from Sicily, Sardinia and Corsica belonged to the first type while the wild plants collected in Apulia showed a higher range of variability and, for some of them, the belonging to the 'oleaster' form of Olea europaea was hypothesized.