Somatic embryogenesis from somatic explants of a Moroccan olive (Olea europaea L.) cultivar, 'Moroccan Picholine'

'Moroccan Picholine' is an important olive cultivar in Morocco. The main objective of this investigation was to develop a protocol for the expression of somatic embryogenesis from adult tissues of this cultivar to allow clonal micropropagation. Very little work has been done on this process from somatic tissues in Moroccan cultivars, particularly on 'Moroccan Picholine', known for its recalcitrance to in-vitro regeneration. Explants used were leaves and petioles, taken from in-vitro-rejuvenated plantlets and cultivated for 6 weeks on four induction media made up of half-strength olive medium (OM/2) as basal medium supplemented with various combinations of plant growth regulators (PGRs): 1) thidiazuron (TDZ) and 3-indolbutyric acid (IBA); 2) TDZ and alpha-naphthaleneacetic acid (NAA); 3) zeatin riboside (ZR) and IBA; and 4) ZR and NAA. Induced calluses were transferred to proliferation medium, consisting of OM supplemented with IBA, for 4 weeks. Grown calluses were subsequently transferred to the expression medium olive cyclic embryogenesis basal medium (ECO) with replenishment of the medium every 4 weeks. For the first time, we observed the formation of somatic embryos from somatic explants of 'Moroccan Picholine'; petioles cultured on the induction medium supplemented with IBA and ZR showed an embryogenesis expression rate of 6.93%, while the induction supplemented with NAA and ZR gave 11.73% for petioles and 7.66% for the intermediate leaf blade. At the same time, adventitious buds were induced when the induction medium was supplemented with TDZ and NAA.