Fig. 1. The general phenylpropanoid biochemical pathway and proposed steps leading to CGA. Enzymes are in black caps and genes in italics. PAL, phenylalanine ammonia lyase, C4H, cinnamate-4-hydroxylase; C3H, coumarate-3-hydroxylase; 4CL, 4-coumaroylCoA ligase; CQT, coumaroylCoA:quinate hydroxycinnamoyl transferase; CHS, chalcone synthase. This sequence of events is based on preferred substrates and time-course studies in other plants, and branchpoints into lignin and flavonoid biosynthesis are shown.