investigating callus induction and quality in four different types of common yew (taxus baccata l.) tissues

Taxus baccata plant is one of the most important sources of the anti-cancer drug taxol. this plant is among the endangered species due to its low growth and reproduction, as well as excessive harvesting from nature. the amount of this valuable drug in the plant is very low. therefore, by using the tissue culture technique, the approach of exploiting this valuable plant to produce taxol can be changed from natural areas to controlled conditions, thus saving it from the danger of extinction and allowing for the extraction of more of this medicine from the plant. in this research, four different types of yew tissue (stem, leaf, shoot tip, and leaf + node) were investigated. for the induction of callus, four types of explants were placed in gamborg culture medium with 6 mg/l 2,4-d, 0.5 mg/l kinetin, and 30 g/l sucrose. after four weeks, callus fresh and dry weight, callus formation rate, callus browning rate, and callus size were investigated. the results showed that the highest fresh and dry weight of callus belonged to the shoot tip tissue, and the lowest fresh and dry weight of callus belonged to the leaf tissue. also, stem tissue and leaf + node tissue showed the highest percentage of callus formation (100%). the results of callus browning showed that the stem tissue browned more than other tissues. examination of the callus size showed that the shoot tip tissue had the largest callus size compared to other tissues.