Figure 1.—

Biosynthesis and accumulation of anthocyanins in maize. (A) Phenylpropanoid biosynthetic pathway leading to the production of anthocyanins. Genes (enzymes) in the pathway are: pal (PAL), phenylalanine-ammonia lyase; c4h (C4H), cinnamic acid hydroxylase; 4cl (4CL), 4-coumaryl:CoA ligase; c2 (CHS), chalcone synthase; chi1 (CHI), chalcone isomerase; f3h (F3H), flavanone 3-hydroxylase; pr1 (F3′H), flavonoid 3′-hydroxylase (* = based on enzyme activity assay); a1 (DFR), dihydroflavanone reductase; a2 (AS), anthocyanidin synthase; bz1 (UFGT), UDP-glucose flavonoid 3-O-glucosyltransferase; and bz2 (GST), glutathione S-transferase. (B) Close-up photos show red and purple aleurones in kernels of pr1 and Pr1 ears, respectively.