Phenylpropanoid pathway
A branching network of plant metabolism that begins with phenylalanine and produces compounds including lignin and flavonoids. Anthocyanins arise from one flavonoid branch.
The phenylpropanoid pathway begins when phenylalanine ammonia-lyase converts the amino acid phenylalanine into cinnamic acid. Subsequent reactions produce shared intermediates that feed several branches of specialized plant metabolism.
Products of those branches include lignin, which strengthens cell walls, and flavonoids Flavonoid A large class of plant compounds covering pigments, UV protectants and antioxidants, found throughout the plant kingdom. Anthocyanins are one flavonoid subclass. with roles in pigmentation, signaling, and responses to stress. Anthocyanins are produced several steps into a flavonoid branch rather than directly from the pathway's first reaction.
Cannabis contains the conserved structural genes needed for these reactions. Studies comparing differently pigmented cannabis leaves have found that expression of several pathway genes correlates with anthocyanin accumulation, but correlation does not show that one gene alone determines color.