The octadecanoid pathway is a biosynthetic pathway for the production of the phytohormone jasmonic acid (JA), an important hormone for induction of defense genes.
JA is synthesized from alpha-linolenic acid, which can be released from the plasma membrane by certain lipase enzymes.
For example, in the wound defense response, phospholipase C will cause the release of alpha-linolenic acid for JA synthesis.
In the first step, alpha-linolenic acid is oxidized by the enzyme lipoxygenase.
This undergoes reduction and three rounds of beta oxidation to form jasmonic acid.