Self- and cross-pollination of some Italian olive genotypes (Olea Europaea L.) and seed endosperm selection by SSR markers

In olive species, the existence of both self- and cross-pollination as reproductive system is mainly due to the flower morphology. However, a high degree of self-incompatibility is known in many genotypes, thus becoming one of the main factor influencing olive yield. Anyway, due to the strong environmental influence, results of compatibility tests are often contradictory, making cultivar classification quite imprecise. The main aim of this research is the evaluation of self-incompatibility values of four Italian olive genotypes (Bella di Spagna, Coratina, Leccino, and Ogliarola barese) widespread in the Mediterranean basin. Moreover, the incompatibility relationships of one of the considered cultivar, i.e. Coratina, were investigated in combination with three pollinizers (Leccino, Oliastro, and Picholine): the in vitro germination potential of progenies were evaluated and only cross-derived embryos were indirectly selected by the molecular profile of the corresponding endosperms. Our results shed some light on the factors affecting olive self-compatibility and provide useful information to farmers about the most effective cultivars to choose for new olive grove or graft planning. Moreover, the endosperm analysis by SSRs represents a new strategy for an accurate, fast and relatively cheap screening of embryos/seedlings.