Somatic embryogenesis and embryo encapsulation in Fraxinus angustifolia Vhal.

This is the first paper on somatic embryogenesis in Fraxinus angustifolia, an important tree for landscaping and wood production. The induction of somatic embryogenesis from immature zygotic embyros and the subsequent maturation, encapsulation and conversion of somatic embryos into plantlets, as well as the long-term maintenance of embryogenic capacity, are reported. The developmental stage of immature zygotic embryos affected morphogenic response. An auxin-cytokinin ratio of 2:1 was essential for induction. 2,4-dichlorphenoxyacetic acid (0.44 ?M) and benzyladenine (4.4 ?M) allowed maintaining the embryogenic capacity for over three years. Mannitol (30 g 1-1) and activated charcoal (2 g l-1) positively affected somatic embryo maturation. The encapsulation of somatic embryos in sodium-alginate beads adversely affected plant conversion. Sixty-five per cent of non-encapsulated somatic embryos were successfully converted into whole plantlets in comparison to 23% of the encapsulated ones