title: The nonmevalonate pathway supports both monoterpene and sesquiterpene formation in snapdragon flowers.
abstract: Terpenoids, the largest class of plant secondary metabolites, play essential roles in both plant and human life. In higher plants, the five-carbon building blocks of all terpenoids, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate, are derived from two independent pathways localized in different cellular compartments. The methylerythritol phosphate (MEP or nonmevalonate) pathway, localized in the plastids, is thought to provide IPP and dimethylallyl diphosphate for hemiterpene, monoterpene, and diterpene biosynthesis, whereas the cytosol-localized mevalonate pathway provides C5 units for sesquiterpene biosynthesis. Stable isotope-labeled, pathway-specific precursors (1-deoxy-[5,5-2H2]-D-xylulose and [2,2-2H2]-mevalolactone) were supplied to cut snapdragon flowers, which emit both monoterpenes and the sesquiterpene, nerolidol. We show that only one of the two pathways, the plastid-localized MEP pathway, is active in the formation of volatile terpenes. The MEP pathway provides IPP precursors for both plastidial monoterpene and cytosolic sesquiterpene biosynthesis in the epidermis of snapdragon petals. The trafficking of IPP occurs unidirectionally from the plastids to cytosol. The MEP pathway operates in a rhythmic manner controlled by the circadian clock, which determines the rhythmicity of terpenoid emission.
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA. dudareva@hort.purdue.edu
authors.forename: Natalia
authors.initials: N
authors.lastname: Dudareva
authors.forename: Susanna
authors.initials: S
authors.lastname: Andersson
authors.forename: Irina
authors.initials: I
authors.lastname: Orlova
authors.forename: Nathalie
authors.initials: N
authors.lastname: Gatto
authors.forename: Michael
authors.initials: M
authors.lastname: Reichelt
authors.forename: David
authors.initials: D
authors.lastname: Rhodes
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Boland
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
mesh_terms: D032161:Antirrhinum / Q000378:metabolism*; D001483:Base Sequence; D002940:Circadian Rhythm; D003600:Cytosol / Q000378:metabolism; D004896:Erythritol / Q000031:analogs & derivatives* / Q000378:metabolism*; D035264:Flowers / Q000166:cytology / Q000378:metabolism; D045782:Hemiterpenes / Q000378:metabolism; D008798:Mevalonic Acid / Q000378:metabolism; D008969:Molecular Sequence Data; D039821:Monoterpenes / Q000378:metabolism*; D009943:Organophosphorus Compounds / Q000378:metabolism; D018087:Plastids / Q000378:metabolism; D012717:Sesquiterpenes / Q000378:metabolism*; D013403:Sugar Phosphates / Q000378:metabolism*
chemical_list: D045782:Hemiterpenes; D039821:Monoterpenes; D009943:Organophosphorus Compounds; D012717:Sesquiterpenes; D013403:Sugar Phosphates; C004809:isopentenyl pyrophosphate; C081898:erythritol 4-phosphate; D004896:Erythritol; D008798:Mevalonic Acid