Effects of culture medium and light on somatic embryogenesis of olive tree (Olea europaea L.) cv. Picholine marocaine.

摘要

Introduction. Until now, no protocol has been developed for the somatic embryogenesis of the Picholine olive tree, a cultivar exploited in nearly 98 percent of the olive tree orchards in Morocco. Thus, our work aimed to study the effects of the culture medium composition and the light on the induction and the development of somatic embryos of this variety. Materials and methods. After disinfection of Picholine olive tree stones, cotyledons were cultured after removal of the zygotic embryos. They were put in petri dishes either totally, or by distinguishing the proximal and distal parts, For the phase of the embryogenic callus induction, four basic culture mediums [Murashige and Skoog (MS), Bourgin and Nitsch (BN), Schenk and Hildebrandt (HS) and Canas and Benbadis (OMc)], with added growth regulators (zeatin and NAA), were tested either in the darkness, or in a 16 h photoperiod. After 6 weeks of culture on these induction media, the calli were transferred into tubes, in fresh culture media but without NAA, and were subjected to a 16 h photoperiod. At the end of this phase, the seedlings with well-developed roots and at least two leaves were transplanted into pots containing a substrate and were acclimatized in a greenhouse. Results. The best results of induction and development of the somatic embryos were obtained with the MS medium and no morphogenesis was observed on the OMc medium. Incubation under light conditions significantly reduced the embryogenic callus induction and inhibited the plantlet regeneration. The cotyledon proximal parts showed better results than the distal parts. The plantlet regeneration rate reached 40 percent of the explants cultured and the survival percentage obtained after their acclimatization reached 94 percent. Conclusion. The protocol described showed the embryogenic capacity of the cv. Picholine marocaine. It could be exploited for the propagation of this olive tree in Morocco.