SOMATIC EMBRYOGENESIS APPROACH FOR SHOOT TIPS OF DATE PALM 'ZAGHLOOL'

This study was conducted to develop a protocol for somatic embryogenesis in shoot-tip-explants of date palm ‘Zaghlool’. Explants formed callus on MS media containing 50 and 100 mg/L 2,4-D or 50 mg/L picloram with 3 mg/L 2iP and 1.5 or 3 g/L activated charcoal. On MS medium with picloram, embryogenic callus was induced while on medium containing 2,4-D non-embryogenic callus derived. Formation of small yellow nodules was noted 8 months after disinfection on picloram enriched medium while white rigid callus was formed on MS with 2,4-D after 4-8 months. After nodule formation, calli were transferred on a MS medium with 10 mg/L 2,4-D, 3 mg/L 2iP and 1.5 g/L activated charcoal for 2-4 months for further development. After that, for somatic embryo development, calli were portioned in samples of 100 mg fresh matter and distributed on 12 regeneration media containing various concentrations of NAA, BAP and activated charcoal. In the first six weeks after transfer on these regeneration media callus mass increased and after six weeks until 18 weeks somatic embryos have been formed. Embryogenic callus mass and number of resultant embryos were significantly increased by NAA. The highest biomass was recorded on MS with 0.1 mg/L NAA with or without activated charcoal; moreover, the highest number of embryos was produced on this medium. Per 100 mg fresh matter of callus on this medium about 8 embryos derived while on hormone-free MS medium only 2 to 4 embryos have been formed. Biomass growth index was recorded in 6-week intervals. The growth index was the highest after transferring to regeneration medium with gradual reduction until 18 weeks. Therefore, after 18 weeks the embryos were transferred to the maturation medium. All somatic embryos matured and germinated on MS medium with 1 mg/L NAA, 1.5 g/L activated charcoal after 8-10 weeks. All shoots rooted on liquid MS with 1 mg/L NAA.