QUANTITATIVE CYTOCHEMICAL-LOCALIZATION OF CINNAMYL ALCOHOL-DEHYDROGENASE ACTIVITY IN PLANT-TISSUES

Although cinnamyl alcohol dehydrogenase is an important enzyme in the biosynthesis of lignins, its localization at the tissue and cellular l evels is not well known. A quantitative cytochemical method has been d evised to determine the localization and level of activity of this enz yme in plant tissues. Unexpectedly, the enzyme activity was present no t only in the developing xylem elements and phloem fibres, but also in the epidermal and subepidermal layers of both roots and shoots. This pattern of localization implies that several distinct sites of cinnamy l alcohol dehydrogenase exist and that the role of this enzyme could b e different according to the cell types in which it is located.