Benzoxazinoid biosynthesis, a model for evolution of secondary metabolic pathways in plants

The benzoxazinoid biosynthetic pathway is of monophyletic origin in the Poaceae. In the dicots Aphelandra squarrosa, Consolida orientalis, and Lamium galeobdolon, benzoxazinoid biosynthesis is analogously organised: The branchpoint is established by a homolog of the alpha-subunit of tryptophan synthase, P450 enzymes catalyse hydroxylations and at least the first hydroxylation reaction is identical in dicots and Poaceae. The toxic aglucon is glucosylated by an UDP-glucosyltransferase.