| Abstract: | Cell wall activities which are related to the final stages oflignin biosynthesis, that is the generation of hydrogen peroxideand peroxidase activity, were investigated using biochemicaland histochemical methods. Peroxidases involved in both reactionsappeared to be restricted to lignifying tissues. Isolated cellwalls exhibited a very high affinity for syringaldazine. Cellwalls were able, in vitro as well as in vivo, to oxidize guaiacolin the absence of H2O2 when NADH was present in the incubationmedium together with p-coumarate and MnCl2 as cofactors. Theorigin of the NADH used to form H2O2 is discussed. Key words: Lignin biosynthesis, Oxidative polymerization, Peroxidases |
