In vitro Shoot Development of Taxus Wallichiana Zucc., a Valuable Medicinal Plant

About 10 genus of Taxus spp. are now disposing in temperate zones at the Northern Hemisphere of which the most popular are Taxus brevifolia Nutt., Taxus baccata L., Taxus wallichiana Zucc. and Taxus cuspidata Siels et Zucc. For the last three decades, Taxus spp. has been concerned after Wani and his colleagues (Triangle Research Institute, NC, USA) discovered a novel anticancer diterpene amide – named “taxol” (paclitaxel) – from the bark of Pacific yew (Taxus baccata) extract (Wani et al., 1971; Edgington, 1991). This compound was approved to have clinical treatment of ovarian and breast cancer by the United States Food and Drug Administration (FDA). In addition, taxol also has a significant activity in the treatment of malignant melanoma, lung cancer, and other solid tumors (Wickremesinhe & Arteca, 1993, 1994). Taxol has also been successfully isolated from other species of the genus Taxus and from different parts of the plant, including pollen, seed, needles, young stems, woody stems, wood, bark and roots (Wani et al., 1971; Vidensek et al., 1990; Witherup et al., 1990; Fett-Neto et al., 1992; Wickremesinhe & Arteca, 1994). The supply of taxol for clinical use is still limited and depends on extraction from the yew plant, as its bark and needle are the main commercial source. Based on the current bark-extraction procedures, nearly 7,000 kg of bark is needed to produce 1 kg of taxol (Cragg et al., 1993). In addition, Taxus species grow very slowly and their seed dormancy is up to 1.5 to 2 years (Steinfeld, 1992). It is very obvious that investigation for alternative sources for the cancer chemotherapeutic agent taxol is urgently needed. Tissue culture of Taxus sp. is being considered as a very promising approach towards providing a long-term source of this valuable compound.