Taxol is a diterpenoid that is produced by Taxus Spp. (Yew trees). It is known as the most effective drug in cancer therapy. In order to improve callus induction and taxol production in Taxus baccata some experiments were performed. These experiments were carried out using factorial design based on CRD. In all experiments, explants (stem and leaf), culture media (B5 and MS) and light conditions (dark and light) were studied. In addition, in the first experiment, BAP and Kin with constant levels of auxin were studied at two levels. In the second experiment, different ratios of auxines; NAA, 2,4-D and cytokinin (Kin) were tested. Results indicated that the most callus induction (97.46%) as well as callus growth (10 mm/two week) were obtained from stem explants on B5 medium supplemented by NAA(2 mg/l), 2,4-D( 0.2 mg/l) and Kin (0.2 mg/l). The light factor did not show any significant effect on either callus induction or growth. In the third experiment, activated charcoal, polyvinyl pyrolidine (PVP), citric acid and ascorbic acid were added to the selected medium for inhibition of callus subculture browning. Results indicated that the above mentioned compounds well inhibited callus browning, but only the media containing ascorbic acid (50 mg/l) rendered suitable cell growth too. Acomparison of xtracted taxol from light and brown calli through HPLC showed that taxol in light calli was 2.45 mg/kg, while being negligible in brown calli (lack of ascorbic acid ).
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