Catalyzes the 3'-O-methylation of the flavonoids luteolin and quercetin (PubMed:9514654). Catalyzes the 3- of 5-O-methylation of the phenylpropanoids caffeate and 5-hydroxyferulate (PubMed:9514654). Substrate preference is 5-hydroxyferulate > luteolin > quercetin > caffeate (PubMed:9514654). Apigenin, kempferol and 3,4-dimethylquercetin do not seem to be substrates for methylation (PubMed:9514654). (E)-5-hydroxyferulate + S-adenosyl-L-methionine = E-sinapate + H(+) + S-adenosyl-L-homocysteine luteolin + S-adenosyl-L-methionine = chrysoeriol + H(+) + S-adenosyl-L-homocysteine quercetin + S-adenosyl-L-methionine = H(+) + isorhamnetin + S-adenosyl-L-homocysteine (E)-caffeate + S-adenosyl-L-methionine = (E)-ferulate + H(+) + S-adenosyl-L-homocysteine a 3'-hydroxyflavone + S-adenosyl-L-methionine = a 3'-methoxyflavone + H(+) + S-adenosyl-L-homocysteine Flavonoid metabolism. Homodimer. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily. It is not sure whether OMT1 and OMT2 are really encoded by two different genes or if they represent cloning artifacts.