Simplified scheme of the phenylpropanoid pathway in tomato. The first committed enzyme in the flavonoid pathway is CHS. The reaction indicated in blue has been proven in vitro in this study, however it is unclear if it occurs in planta. Enzymes are given in bold italics. PAL: phenylalanine ammonia-lyase. C4H: cinnamate 4-hydroxylase. 4CL: 4-coumarate: CoA ligase. CHS: chalcone synthase. CHI: chalcone isomerase. F3H: flavanone 3-hydroxylase. FLS: flavonol synthase. F3'H: flavonoid 3'-hydroxylase. F3'5'H: flavonoid 3'5'-hydroxylases. DFR: dihydroflavonol 4-reductase. ANS: anthocyanidin synthase. UFGT: UDP glucose flavonoid 3-O-glucosyl transferase.