Suitable Mn, Zn and Cu concentrations in the culture media and proper harvest time for Taxus media cv “Hicksii”

【Objectives】 Paclitaxel (Taxol) shows excellent antitumor activity against breast cancer, ovarian cancer and non-small cell lung cancer, is one of the best chemotherapeutic agents developed from plant sources. Taxus production has received attention as an important natural material for extracting taxol. The purpose of this study was to study the effects of mircoalements (Mn, Zn and Cu) on the growth and paclitaxel accumulation in seedlings of Taxus, providing a basis for the optimum harvest period and the rational application of micronutrient fertilizer.【Methods】 A sand culture experiment was conducted and the seedlings of 3-year-old and 5-year-old Taxus media cv “Hicksii” were growen. Five concentration of Mn 0, 4.50, 9.00, 13.50 and 18.00 μmol/L, Zn 0, 0.15, 0.30, 0.45 and 0.60 μmol/L, and Cu: 0, 0.40, 0.80, 1.20 and 1.60 μmol/L were designed, each treatment replicated three times.Branches and leaves of plants were collected monthly from March 15, 2012 to October 15, 2012. The paclitaxel accumulation contents was determined with high-performance liquid chromatography (HPLC) method, the seedling growth were observed in November 15, 2012, the biomass were weighed at the same time. 【Result】 1) Mn, Zn and Cu treatment levels significantly affect the growth and paclitaxel contents, increase the plants heights, crossing diameters and shoot length, increase the weights of branches, leaves and roots of the saplings. For the growth of seedlings, the optimum treatment is Cu 0.15 μmol/L for 5-year-old seedlings and 0.30 μmol/L for3-year-old seedlings, Mn 9.00 μmol/L and Zn 0.40 μmol/L for the two ages of seedlings. For paclitaxel accumulation, the optimum level is Zn 0.40 μmol/L and Cu 0.30 μmol/L for the both ages, and Mn 9.00 μmol/L for the 3-year-old and 4.50 μmol/L for5-year-old saplings. When the micronutrient treatment levels exceeded the optimum one, the paclitaxel accumulation will be inhibited and the higher the treatment levels, the stronge the inhibition. 2) The paclitaxel content in 5-year-old plants are significantly higher than in3-year-old ones under all the treatments, and the differences are significant at harvest. 3) The paclitaxel content start to decrease from March to June, and is lowest in June, then increase and keep relatively stabile in September and October. The effects of Mn on the paclitaxel accumulation is higher than Zn and higher than Cu, no matter their treatment concentrations.【Conclusions】 The paclitaxel content in 5-year-old saplings is significantly higher than the 3-year-old ones, the proper harvest time for obtaining high paclitaxel content of saplings is September and October. The optimum treatment level is Mn 9.00 μmol/L, Zn 0.40 μmol/L and Cu 0.15-0.30 μmol/L.