Converts the unstable imine alcohols produced by CYP71D1V2/T3O into 3-hydroxy-16-methoxy-2,3-dihydrotabersonine or 3-hydroxy-2,3-dihydrotabersonine. (3R)-3-hydroxy-16-methoxy-2,3-dihydrotabersonine + A = (3R)-1,2-didehydro-3-hydroxy-16-methoxy-2,3-dihydrotabersonine + AH2 (3R)-3-hydroxy-2,3-dihydrotabersonine + A = (3R)-1,2-didehydro-3-hydroxy-2,3-dihydrotabersonine + AH2 Binds 2 Zn(2+) ions per subunit. Alkaloid biosynthesis; vindoline biosynthesis. Expressed in leaf epidermis. Up-regulated by herbivory. Belongs to the zinc-containing alcohol dehydrogenase family. Truncated N-terminus.