Oxidation of coniferyl alcohol by cell wall peroxidases at the expense of indole-3-acetic acid and O 2: A model for the lignification of plant cell walls in the absence of H 2O 2

Abstract

The oxidation of coniferyl alcohol (CA), a lignin precursor, by cell wall peroxidases may take place at the expense of indole-3-acetic acid (IAA) and O 2, and in the absence of H 2O 2. The peroxidase-catalyzed oxidation of CA shows an optimum at an IAA concentration of 0.33 mM, while higher IAA concentrations are inhibitory. The observation that the oxidation of CA by cell wall peroxidase at the expense of IAA and O 2 is inhibited by genistein, a putative endogenous inhibitor of lignification in lupin hypocotyls, supports the view that the H 2O 2-generating system coexists with cell wall peroxidase activities involved in lignification, and that it takes place at the expense of IAA and O 2.