Cytokinin hydroxylase that catalyzes the biosynthesis of trans-zeatin via the isopentenyladenine riboside 5'-monophosphate (iPRMP)-dependent pathway. Can use isopentenyladenosine-5'-monophosphate, isopentenyladenosine-5'-diphosphate and isopentenyladenosine-5'-triphosphate as substrate. H(+) + N(6)-(dimethylallyl)adenosine 5'-phosphate + NADPH + O2 = 9-ribosyl-trans-zeatin 5'-phosphate + H2O + NADP(+) H(+) + N(6)-(dimethylallyl)adenosine 5'-diphosphate + NADPH + O2 = 9-ribosyl-trans-zeatin 5'-diphosphate + H2O + NADP(+) H(+) + N(6)-(dimethylallyl)adenosine 5'-triphosphate + NADPH + O2 = 9-ribosyl-trans-zeatin 5'-triphosphate + H2O + NADP(+) Expressed in roots and flowers. By trans-zeatin and isopentenyladenine in roots. Down-regulated by auxin and abscisic acid in roots. Belongs to the cytochrome P450 family. Sequencing errors.