Involved in the foliar biosynthesis of vindoline, a precursor of vinblastine and vincristine (PubMed:24108213). Hydroxylates specifically tabersonine, 2,3-dihydrotabersonine and 2,3-dihydro-3-hydroxytabersonine, but has no activity with naringenin, tryptamine, secologanin, strictosidine, ajmalicine, vindoline and catharanthine (PubMed:24108213). (-)-tabersonine + O2 + reduced [NADPH--hemoprotein reductase] = 16-hydroxytabersonine + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Expressed at low levels in roots, fruits, stems, flower buds and flowers, but highly expressed in young leaves. Detected in adaxial and abaxial epidermis cells. Not regulated by methyl jasmonate treatment. Tabersonine 16-hydroxylation is orchestrated in an organ-dependent manner by two genes including CYP71D351, which encodes the T16H2 isoform acting in the foliar vindoline biosynthesis, and CYP71D12, which encodes the T16H1 isoform acting in the flower vindoline biosynthesis. Belongs to the cytochrome P450 family.