Cytochemical Localization of Hydrogen Peroxide in Lignifying Cell Walls

The presence of endogenous H2O2 was demonstrated at the electron microscope level with the CeCl3 technique in lignifying cell walls of poplar. Reaction product was precisely located in the very same walls which could oxidize hydrogen donors in the absence of exogeneous H2O2. As evidenced by these results, peroxidases are truly involved in the polymerisation of lignin monomers even if other oxidases may participate in this biosynthetic pathway.