Indirect somatic embryogenesis of date palm using juvenile leaf explants and low 2,4-D concentration

This chapter describes an efficient protocol for large-scale micropropagation of date palm. Somatic embryo-derived plants are regenerated from highly proliferating suspension cultures. Friable embryogenic callus is initiated from juvenile leaves using slightly modified Murashige and Skoog (MS) medium supplemented with 0.1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D). Suspension cultures consisting of proembryonic masses are established from highly competent callus for somatic embryogenesis using half-strength MS medium enriched with 0.1 mg/L 2,4-D and 300 mg/L activated charcoal. The productivity of cultures increased 20-fold when embryogenic cell suspensions were used instead of standard protocols on solidified media. The overall production of somatic embryos mostly exceeds 10,000 units per liter per month. Partial desiccation of mature somatic embryos, corresponding to a decrease in water content from 90 down to 75%, significantly improved germination rates. (Résumé d'auteur