Proliferation and germination of somatic embryos from embryogenic suspension cultures in Phœnix dactylifera

Abstract

The present study demonstrates a procedure for the rapid development of a high number of somatic embryos from embryogenic suspension culture. This method might be efficient for mass propagation of Phœnix dactylifera L. Embryogenic callus placed in liquid medium with 10⁻⁵ M ABA yielded an average 72 embryos per 100 ml of culture medium within 2 months, while those placed on solid medium yielded an average of 33, 20 and 16 embryos per 100 ml of culture medium respectively for 10⁻⁷, 10⁻⁶ and 10⁻⁵ M ABA after 4 months. The combination of 2,4-DIchlorophenoxyacetic acid (2,4-D) (4.5 × 10⁻⁷ M), glutamine (6.7 × 10⁻⁴ M), and ABA (10⁻⁵ M) (L8 liquid medium) showed a beneficial effect on somatic embryos production compared to 2,4-<sc>D</sc> and glutamine alone, while this combination significantly ( p < 0.05) increased the accumulation of storage proteins (144 and 138 mg g⁻¹ DW respectively for Jihel and Bousthami noir cultivars) in somatic embryos. The somatic embryos which underwent maturation on medium containing only 4.5 × 10⁻⁷ M 2,4-<sc>D</sc> and 10⁻⁵ M ABA (L6 liquid medium) accumulated more sugars (292 and 265 mg g⁻¹ DW respectively for Jihel and Bousthami noir) than those matured on any other liquid medium. Histological studies revealed that somatic embryos (developed in L6 and L8 liquid media) accumulated less reserve compounds (proteins and sugars) than zygotic embryos. The addition of activated charcoal (0.25 and 0.5 g l⁻¹) and phytagel^® (2.5 g l⁻¹) to the germination medium may be useful for enhancing the germination of Phœnix dactyliferasomatic embryos.