Molecular cloning and functional analysis of the ortho-hydroxylases of p-coumaroyl coenzyme A/feruloyl coenzyme A involved in formation of umbelliferone and scopoletin in sweet potato, Ipomoea batatas (L.) Lam.

► Ortho-hydroxylation of cinnamates is a key step in coumarin formation. ► The Fe(II) and 2-oxoglutarate dioxygenases as the ortho-hydroxylases of sweet potato were cloned. ► The corresponding recombinant enzymes catalyze ortho-hydroxylation toward p-coumaroyl-CoA and/or feruloyl-CoA. ► Expression of these genes and increased levels of coumarins in sweet potato were induced concomitantly.