Maturation and Germination of Date Palm (Phoenix dactylifera L.) Somatic Embryos

Abstract

Maturation and germination of somatic embryos are two crucial steps in the somatic embryogenesis process. Herein, we evaluated the effects of several factors on the maturation and germination of date palm somatic embryos. Globular somatic embryos of cv. ‘Najda’ were cultured on Murashige and Skoog medium at full strength (MS), half strength (1/2MS), and one-third strength (1/3MS), with or without agar, and supplemented with various concentrations of mannitol, sorbitol, polyethylene glycol (PEG, MW 8000) and abscisic acid (ABA). Our results showed that culture medium strength and texture (liquid or semi-solid), osmotic agents, and the concentration and time of exposure to ABA influence somatic embryo maturation. The highest mean number of mature somatic embryos (106.4 per 100 mg fresh weight callus) was obtained after 3 weeks of culture on full-strength liquid MS medium supplemented with 30 g L-1 PEG and 40 μM ABA, followed by 9 weeks of culture on the same medium but without ABA. Somatic embryo germination was achieved by transferring mature embryos to MS medium containing various combinations of 1-naphthalene acetic acid (NAA), 6-benzylaminopurine (BAP) and gibberellic acid (GA3). The highest germination rate (68%) of somatic embryos occurred in the presence of 0.5 mg L-1 NAA. However, there was no significant difference with the other germination media (54-66%). Plantlet acclimatization was successfully accomplished, and the survival rate was 80% after 6 months in the glasshouse. The findings of the present study open new prospects for massive propagation of this bayoud-resistant date palm cultivar.

Keywords

• embryogenic culture
• osmotic agents
• Phoenix dactylifera L.
• plant growth regulators
• somatic embryogenesis