Hydrogen peroxide is required for poly(phenolic) domain formation during wound-induced suberization

The requirement for hydrogen peroxide (H2O2) during suberization was demonstrated ill wound-induced potato tubers by monitoring the extent of phenolic polymerization after the inhibition of H2O2 production using diphenyleneiodonium (DIPI). In DIPI-treated tissues the extent of phenolic polymerization in suberized tissues, measured using DFRC (Derivatization Followed by Reductive Cleavage) and thioglycolic acid analyses, was greatly reduced relative to untreated controls. Concomitantly, a large quantity of new soluble phenolics accumulated in the DPI-treated tissue some of which were not present in the controls. We suggest that the inhibition of H2O2 production prevented these phenolics from being oxidized by cell wall peroxidases. As a result, these phenolics were left unpolymerized and accumulated in the tissue. Several of the soluble phenolics were identified as hydroxycinnamic acid derivatives. From the data presented, it was concluded that H2O2 is required for the polymerization step in the formation of the poly(phenolic) domain of suberized potato tubers.