O-methyltransferase involved in the biosynthesis of furocoumarins natural products such as bergapten, a photosensitizer used for medical purpose such as treating psoriasis and vitiligo or facilitating resistance to microbial infection and other stresses (PubMed:30934718, PubMed:27252733, PubMed:31666994). Catalyzes specifically the methylation of bergaptol (PubMed:30934718, PubMed:27252733, PubMed:31666994). Not active on xanthotol, isoscopoletin, scopoletin and esculetin (PubMed:30934718, PubMed:27252733). bergaptol + S-adenosyl-L-methionine = bergapten + S-adenosyl-L-homocysteine Aromatic compound metabolism. Secondary metabolite biosynthesis. Homodimer. Mostly expressed in roots and, to a lower extent, in stems and leaves. Induced by methyl jasmonate (MeJA). The high-activity Ile-320 mutant could be used in metabolic engineering to produce bergapten in order to treat depigmentation disorder. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily.