Removal of H(2)O(2), oxidation of toxic reductants, biosynthesis and degradation of lignin, suberization, auxin catabolism, response to environmental stresses such as wounding, pathogen attack and oxidative stress. These functions might be dependent on each isozyme/isoform in each plant tissue. Closely linked to lignin formation by showing monolignol substrate specificity. 2 a phenolic donor + H2O2 = 2 a phenolic radical donor + 2 H2O Binds 2 calcium ions per subunit. Binds 1 heme b (iron(II)-protoporphyrin IX) group per subunit. Mainly expressed in roots. There are 73 peroxidase genes in A.thaliana. Belongs to the peroxidase family. Classical plant (class III) peroxidase subfamily.