Complete biosynthesis of salicylic acid from phenylalanine in plants

Abstract Salicylic acid (SA) is a pivotal phytohormone for plant responses to biotic and abiotic stresses. Plants have evolved two pathways to produce SA: the isochorismate synthase and phenylalanine ammonia lyase (PAL) pathways 1 . Whereas the isochorismate synthase pathway has been fully identified 2–4 , the PAL pathway remains incomplete. Here we report the full characterization of the PAL pathway for SA biosynthesis via functional analysis of rice ( Oryza sativa ) SA-DEFICIENT GENE 1 ( OSD1 ) to OSD4 . The cinnamoyl-coenzyme A (CoA) ligase OSD1 catalyses the conversion of trans -cinnamic acid to cinnamoyl-CoA, which is subsequently transformed to benzoyl-CoA via the β-oxidative pathway in peroxisomes. The…