2-hydroxyisoflavanone 4'-O-methyltransferase involved in the biosynthesis of formononetin. Can use 2,7,4'-trihydroxyisoflavanone as substrate, but not daidzein. a 4'-hydroxyisoflavone + S-adenosyl-L-methionine = a 4'-methoxyisoflavone + H(+) + S-adenosyl-L-homocysteine (2R,3S)-2,4',7-trihydroxyisoflavanone + S-adenosyl-L-methionine = (2R,3S)-2,7-dihydroxy-4'-methoxyisoflavanone + H(+) + S-adenosyl-L-homocysteine Up-regulated by elicitor. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily.