Studies on the effects of growth conditions on taxanes in Taxus canadensis

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University of New Brunswick


This study focused on analyzing the effects of growth site, foliar harvest date, shade coverage, and clone to analyze the three major commercially important taxanes in T. canadensis roots, needles and stems: 10-deacetylbaccatin III (10-DAB III), 9-dihydro-13-acetylbaccatin III (9-DHB III), and paclitaxel (PAC). The results indicate that full sun (no shade) was beneficial for needles to accumulate higher 10-DAB III concentrations and stems to accumulate higher PAC concentrations. In contrast high shade coverage (65%) is optimal for needles to accumulate higher PAC concentrations and stems to accumulate higher 10-DAB and 9-DHB III concentrations. For roots, samples with 35% shade coverage had higher 10-DAB III concentration, while shade coverage did not have any effect on 9-DHB III and PAC in the roots. When aiming for total yield only in needles and stems, plants under high shade coverage had higher amount of taxanes. If compared strictly by total yield in needles, stems and roots, then foliage with no shade coverage would be optimal, which would be an important consideration for commercial production. For the same six clones situated within each treatment, the concentrations of taxanes in clones KC was higher than the other clones. The best date for commercial harvesting was September for needles and November for stems. Moreover, tracking chlorophyll variation under different nursery conditions would be a better choice to track the yield of three major taxanes. Since PSII photochemistry (Fv/Fm), Ca, Cb, C (x+c), C (a+b) and Chl (a+b)/ (x+c) have the same variation with three major taxanes, while the ratio of Ca/Cb variation is opposite to three major taxanes. Keywords: T. canadensis, paclitaxel, HPLC, chlorophyll fluorescence, commercialization