Somatic embryogenesis and plant regeneration in date palm Phœnix dactylifera L., cv. Boufeggous is significantly improved by fine chopping and partial desiccation of embryogenic callus

Abstract

Plant regeneration through somatic embryogenesis from young leaf explants (5-10 mm long) adjacent to the apex of 5-6 year old offshoots of Tunisian date palm (Phoenix dactylifera L.), cultivar Boufeggous was successfully achieved. Factors affecting embryogenic callus initiation, including plant growth regulators and explant size, were investigated. The highest induction frequencies of embryogenic calli occurred after 6-7 months on MS medium supplemented with 10 mg l -1 2,4-D and 0.3 mg l -1 activated charcoal. The subculture of these calli onto maintenance medium resulted in the formation of proembryos. Fine chopping and partial desiccation (6 and 12 h) of embryogenic calli with proembryos prior to transfer to MS medium supplemented with 1 mg l -1 ABA stimulated the rapid maturation of somatic embryos. Maturated somatic embryo yield per 0.5 g FW of embryogenic callus was 51 embryos with an average maturation time of 55 days. This was increased to 422 with finely chopped callus, and 124 and 306 embryos following 6 and 12 h desiccation treatments, respectively. The average time to maturation for these 3 treatments was 35, 43 and 38 days, respectively. Subsequent substitution of ABA in MS medium with 1 mg l -1 NAA resulted in the germination and conversion of 81% of the somatic embryos into plantlets with normal roots and shoots. The growth of regenerated somatic plants was also monitored in the field.

Effect of carbohydrate source on the in vitro germination of Elaeis guineensis Jacq. zygotic embryos on two basal media

“…The presence of the hydrolytic enzyme "invertase" in plant cell wall and vacuole that breaks down sucrose into glucose and fructose for plant metabolism may be responsible for the superiority of sucrose over other carbon sources (Arnd and Guo-Qing, 1999). The superiority of sucrose over the other sugars employed as carbon source in this study is consistent with earlier reports for other plants such as Phoenix dactylifera (Veramendi and Navarro, 1996;Othmani et al, 2009) used as a sole carbon source and Dianthus caryophyllus (Karami et al, 2006). Baskaran and Jayabalan (2005) suggested that among the three carbon sources, sucrose proved to be better than fructose or glucose for shoot regeneration of Eclipta alba.…”

Micropropagation of Date Palm: A Review

“…Nevertheless, such explants are not appropriate for true-to-type propagation [18]. Different methods have been described for explant disinfection, and the main disinfecting solutions used are sodium hypochlorite [19,20] and mercuric chloride [21,22]. In addition, antioxidant additives such as ascorbic acid, citric acid, polyvinylpyrolydon (PVP), anhydrous caffeine and/or sodium diethyldithiocarbonate have been widely used during disinfection in order to reduce explant browning [12,13,19,20].…”

“…Othmani et al reported the formation of somatic embryos after 6-7 months of induction in date palm cv. Boufeggous [21]. In date palm cvs.…”

“…Khalas [26] while Othmani et al reported that fine chopping and partial desiccation of embryogenic calli stimulate somatic embryo maturation in cv. Boufeggous [21].…”

“…In cv. Boufeggous, Othmani et al (2009a) indicated that 1 mg/L NAA resulted in the germination and conversion into plantlets of 81% of somatic embryos [21]. Al-Khayri reported that the concentration of NAA, IBA as well as the medium strength influence somatic embryo germination [32].…”