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  • Author or Editor: Enaksha R. Wickremesinhe x
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Enaksha R. Wickremesinhe and Richard N. Arteca

Fast growing callus was derived from Cephalotaxus harringtonia stem explants placed on MS basal salt medium with B-5 vitamins, 3% sucrose, 1 μM kinetin and 4.5 μM 2,4-D. Callus placed on basal medium with 10 μM kinetin and 0.45 μM 2,4-D turned green and organogenesis was observed upon subculture onto basal medium without hormones. Shoots were excised and placed on 1/2 strength MS salts and 10% sucrose for further shoot development. During the process of organogenesis, we also observed the differentiation of roots. Rapidly growing root cultures were established by culturing them under a 24 hour light regime of 35 μM/m2/s. Two grams of root tip explants cultured on B-5 medium with 2% sucrose were capable of producing an average of 24 grams of roots within 11 days. A 20-fold increase in fresh weight was achieved within 3 weeks when 15 grams of these roots were cultured in a 3 liter air-sparged bioreactor. C. harringtonia contains a number of alkaloids that exhibit cytotoxicity and are being evaluated as chemotherapeutic agents. We are currently in the process of establishing growth characteristics for these roots and assaying roots for the presence of these alkaloids. All cultures were grown under a 12 hour light regime unless otherwise stated.

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Enaksha R. Wickremesinhe and Richard N. Arteca

Cephalotaxus harringtonia plants produce alkaloid compounds possessing antitumor properties, the major one being homoharringtonine. The purpose of this study was to produce roots from callus cultures developed earlier. Fast growing callus cultures were placed on MS basal salt medium with B-5 vitamins, 2% sucrose, 10 μM kinetin, 0.45 μM 2,4-D and 0.2% Gelrite. Upon subculture onto basal medium without hormones, we observed organogenesis of both shoots and roots. Roots were excised and established on basal medium without hormones. By subculturing two 2-inch root tips containing numerous visible laterals in liquid medium we were able to harvest 30 g of roots/250 ml flask after 3 weeks and 50 g/250 ml flask after 6 weeks. A 20-fold increase in fresh weight was achieved within 3 weeks when 15 grams of roots were initially seeded into a 3 liter air-sparged bioreactor. However, most of these roots appeared to be fleshy/swollen while root cultures established from half inch root tips grew slower but were normal in appearance. We arc currently in the process of establishing growth characteristics for these roots and assaying roots for the presence of these alkaloids.