Releases hydrogen peroxide in the apoplast. May play an important role in several aspects of plant growth and defense mechanisms. 2 H(+) + O2 + oxalate = 2 CO2 + H2O2 Oligomer (believed to be a pentamer but probably hexamer). Root. By salt stress. Glycosylated. A form called G contains antennary GlcNAc residues, whereas a form called G' lacks antennary GlcNAc residues in its otherwise identical glycans. Belongs to the germin family.