Multiple origins for Mediterranean olive (Olea europaea L. ssp. europaea) based upon mitochondrial DNA polymorphisms

A study of nuclear and cytoplasmic genetic diversity of cultivated olive, oleaster and other taxa belonging to the complex O. europaea was performed. Nuclear DNA polymorphism (RAPDs) in oleaster displays a gradient between the east and west of the Mediterranean Basin. In cultivars, the gradient is less visible owing to their diffusion and selection. Furthermore, three mitotypes (ME1, MOM and MCK) were detected in both cultivated olive and oleaster. A fourth mitotype, ME2, was unique to some cultivars. The preponderant mitotype, ME1, marks the Near Eastern origin of olive in oleaster. In the west of the Mediterranean, another mitotype, MOM, was found in most oleaster. and a few cultivars. The third, MCK, was found in a few oleaster from the west and in cultivars originating in Kabylie and Languedoc. We argue that MCK marks an ancestral Mediterranean population. The mitotypes mark independent cultivated olive origins which were not detected with DNA nuclear diversity.