Effect of growth regulators and antioxidants in the medium on in vitro callus induction in European yew (Taxus baccata L.)

Yew plant is major source of Taxol, highly effective anti cancer medicine, and cell culture is one way to increase its production. A factorial experiment using B5 as base medium was designed to obtain a proper hormonal and antioxidant composition in callus induction media for European yew existing in Iran. Four different hormonal mixes including 1) 4.5 mg/l 2,4-D, 1mg/l kinetin and 0.33 mg/l GA3; 2) 2 mg/l NAA, 0.2 mg/l 2,4-D and 0.2 mg/l kin; 3) 2 mg/l 2,4-D, 0.5 mg/l NAA and 0.5 mg/l GA3; and 4) 2 mg/l 2,4-D, 0.5 mg/l NAA and 0.5 mg/l kin as the first factor, and two different antioxidants PVP and ascorbic acid as the second factor were conducted on complete random design with 8 replications during 2 months periods. The percentage of callus induction and total callus weight were measured and the ratio of callus weight increment was calculated. Hormonal compositions and the interaction between 2 factors significantly affected percentage of callus induction during the first period, but no significant effect was observed for antioxidants alone. No significant difference observed between total callus weights during the first period, but significant effects were shown for hormonal mixtures, antioxidants, and their interaction observed during the second period. The ratios of callus weight increment also was significantly different between hormonal mixtures and antioxidants. Therefore, tissue culture process should follow out by two steps with two media; in first 2,4-D have to use to maximize callus induction, but need to permit induced calli to grow sufficiently during thereafter months on medium with NAA instead 2,4-D, to obtain high quality calli. Ascorbic acid has to use in any media as antioxidant.