Abstract: The contents of taxol and its two important precursors,namely baccatin III(B III)and 10-deacetylbaccatin III (10-DAB) in various tissues of yew trees Taxus chinensis(Pilg.)Rehd. at different ages in different seasons were quantified by HPLC.The results indicated that the content of taxol decreased successively according to stem barks,root barks,lateral stem barks,seeds,fibres,twigs and young needles in a single tree.The gradient distribution of taxol concentration along radial direction of cross section of lateral stem was surveyed for the first time.It was found that the highest amount of taxol occurred in the secondary xylem rather than in the cortex of the lateral stem.The highest and the lowest contents of 10-DAB and B III among the parts of a tree occurred in needles and fibres,respectively.The content of 10-DAB in needles was in a range of 0.01% to 0.02%,higher than that of B III and taxol.The result of the absence of both taxol and related taxanes in needles from 2-3 years old yew tree indicated that the biosynthesis of taxanes may require related phase of the development of the plant.It was observed that the mature needles in the spring have higher amount of taxol than in autumn,while the case of 10-DAB was in reverse.The mechanisms of (biosynthesis) and accumulation of taxol were discussed through the analysis of the distribution of taxol and related (compounds) in T.chinensis(Pilg.)R.

Key words: yew tree [Taxus chinensis(Pilg.)Rehd.], taxanes, taxol