Plant lipoxygenases may be involved in a number of diverse aspects of plant physiology including growth and development, pest resistance, and senescence or responses to wounding. Required for the regulation of wound-induced gene expression, but is not involved in the bulk production of jasmonate upon wounding. Catalyzes the hydroperoxidation of lipids containing a cis,cis-1,4-pentadiene structure. Linolenic acid is the preferred substrate, before linoleic and arachidonic acids. (9Z,12Z)-octadecadienoate + O2 = (13S)-hydroperoxy-(9Z,11E)-octadecadienoate (9Z,12Z,15Z)-octadecatrienoate + O2 = (13S)-hydroperoxy-(9Z,11E,15Z)-octadecatrienoate Binds 1 Fe cation per subunit. Optimum pH is 6.0. Lipid metabolism; oxylipin biosynthesis. Monomer. Expressed in roots and leaves. Detected in tubers and flower buds. Up-regulated localy and systemically 30 minutes after wounding. Up-regulated by jasmonate and abscisic acid treatment. Not induced by pathogen infection. Depletion of LOX-H3 by co-suppression-mediated gene silencing leads to higher tuber yield, but has no effect on the number of tubers per plant. Belongs to the lipoxygenase family.