IN VITRO CLONING OF DATE PALM PHOENIXDACTYLIFERA L., CV. DEGLET BEY BY USING EMBRYOGENIC SUSPENSION AND TEMPORARY IMMERSION BIOREACTOR (TIB)

摘要

The present work is the first report on in vitro regeneration of an elite date palm cultivar, Deglet Bey (Mnakher) through both somatic embryogenesis and direct shoot formation from young leafexplants cultured on MS agar-solidified medium supplementedwith 10 mg.l~(-1) 2,4-dichlorophenoxyacetic acid for 8 months. Factors affecting embryogenic callus and shoot initiation, including antioxidants, adsorbents and 2,4-D concentrations, were investigated. Embryogenic suspensions and culture of shoots in temporary immersion bioreactor (TIB) were developed to improve differentiation of embryogenic callus and proliferation of regenerated shoots, respectively. The yield ofcotyledonary somatic embryos produced in half-strength MS liquid media, especially whenenriched with 2 mg.l1 2,4-dichlorophenoxyacetic acid, were shown to be greater than in agar-solidified medium, namely 501 versus 29 per 0.5 g fresh weight of embryogenic callus. The culture of shoot clusters in TIB with an immersion frequency of 5 min every 8 h with MS liquid medium containing 0.04 mg.l'1 a-naphthalenacetic acid, 0.2 mg.l'1 6-benzylaminopurine 0.02 mg.l'1 kinetinfor 6 weeks has clearly improved the yield of regenerated shoots per 15 g of shoot clusters. Indeed, it increased 5.5-fold incomparison with that regenerated on agar-solidified medium. For development into plantlets, cotyledonary somatic embryos and regenerated shoots were cultured on MS agar-solidified medium free of 2,4-D and MS medium comprising 0.1 mg.l'1 NAA, respectively.