The invention provides recombinant polynucleotides comprising a nucleic acid encoding a CYP76AD6 or related gene and their use for producing L-DOPA from tyrosine and treating dopamine-responsive disorders, such as Parkinson's Disease. The invention also provides recombinant polynucleotides comprising a nucleic acid encoding a CYP76AD1 and/or CYP76AD6, a nucleic acid encoding a DOPA 4.5-dioxygenase (DOD) enzyme, such as Beta vulgaris DODA1, and, in some cases, a nucleic acid encoding betalain related glucosyltransferase, such as M. jalapa gene cyclo-DOPA 5-O-glucosyltransferase (cDOPA5GT), and their use for producing betalains. Finally, the invention provides chimeric polypeptides, expression vectors, cells, compositions, and organisms, including plants, and their uses in various methods of the invention.