IMMUNOCYTOCHEMICAL LOCALIZATION OF TAXOL IN TAXUS-CUSPIDATA

The supply of taxol, a valuable anticancer compound, depends completel y on the extraction of taxol from Taxus brevifolia (Pacific yew) plant s. Although ta?tol is found in virtually all parts of the plant, nothi ng is known about the localization of taxol within the cells or tissue s of the plant. Portions of T, cuspidata stems were chemically fixed, dehydrated in ethanol, and then embedded in standard resins. In these tissues, immunolocalization using polyclonal antitaxol antiserum indic ates that taxol is associated with vacuolar tannin inclusions in axial phloem parenchyma cells. Little or no label is bound over the cell wa lls of any cell type. However, chemical preparation causes diffusion o f taxol, which results in an erroneous localization of taxol. In contr ast, using cryotechniques and a water-soluble melamine resin (Nanoplas t), taxol is localized almost exclusively in the cell walls of phloem, vascular cambium, and xylem. Our method yields insight into the probl ems associated with the intra- and extracellular localization of lipop hilic plant secondary compounds. It also offers an alternative tissue- preparation protocol that could be useful for the localization of othe r plant metabolites.