Cytochrome P450 of the CYP74A subfamily involved in the biosynthesis of jasmonic acid from lipoxygenase-derived hydroperoxides of free fatty acids. Catalyzes the synthesis of unstable allene oxide, which is further converted spontaneously by hydrolysis or cyclization. Metabolizes 13- but not 9-hydroperoxides of linoleic and linolenic acids. Can use 15S-hydroperoxy-11(Z),13(E),17(Z)-eicosatrienoic acid (15-HPET) and 13S-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid (13-HPOT) as substrates, but only 50% activity with 13S-hydroperoxy-9(Z),11(E)-octadecadienoic acid (13-HPOD). (13S)-hydroperoxy-(9Z,11E,15Z)-octadecatrienoate = (9Z,13S,15Z)-12,13-epoxyoctadeca-9,11,15-trienoate + H2O Expressed in flower buds, leaves, roots, stems, petioles and cotyledons (PubMed:10859201). Not detected in ripe fruits (PubMed:10859201). Expressed in sieve elements (PubMed:12826630). Up-regulated by wounding in local and systemic leaves. Belongs to the cytochrome P450 family.