The biosynthesis of thymol, carvacrol, and thymohydroquinone in Lamiaceae proceeds via cytochrome P450s and a short-chain dehydrogenase
Sandra T. Krause, Pan Liao, Christoph Crocoll, Benoît Boachon, Christiane Förster, Franziska Leidecker, Natalie Wiese, Dongyan Zhao, Joshua C. Wood, C. Robin Buell, Jonathan Gershenzon, Natalia Dudareva, Jörg Degenhardt
Abstract
Significance The monoterpene alcohols thymol, carvacrol, and thymohydroquinone are characteristic flavor compounds of thyme, oregano, and other Lamiaceae. These specialized metabolites are also valuable for their antibacterial, anti-spasmolytic, and antitumor activities. We elucidated the complete biosynthetic pathway of these compounds, which starts with the formation of γ-terpinene from geranyl diphosphate. The aromatic backbone of thymol and carvacrol is formed by P450 monooxygenases in combination with a dehydrogenase via an unstable intermediate. Additional P450s hydroxylate thymol and carvacrol to form thymohydroquinone. Our findings demonstrate a mechanism for the formation of phenolic monoterpenes that differs from previous predictions and provides targets for metabolic engineering of high-value terpenes in plants.