Jasmonic acid (JA), is a growth inhibitor, senescence-promoting substance. Jasmonates, such as jasmonic acid, are cyclopentanone derivatives synthesized from linolenic acid via the octadecanoic pathway. JAs is structurally related to prostaglandins, which are autacoidal hormones found in mammals. JA is synthesized from alpha-linolenic acid, which is a C18 poly-unsaturated fatty acid. It is synthesized from plant membranes by enzymes similar to lipase. Key JA biosynthetic enzymes have chloroplast transit peptides that directing their import into the chloroplast. Key enzymes include lipoxygenase, allene oxide synthase, and allene oxide cyclase.