Biosynthesis of mono- and sesquiterpenes in carrot roots and leaves (Daucus carota L.): metabolic cross talk of cytosolic mevalonate and plastidial methylerythritol phosphate pathways.
The biosynthesis of the monoterpenes terpinolene and myrcene and the sesquiterpene beta-caryophyllene in roots and leaves of two carrot varieties (Daucus carota L. cultivars Bolero and Kazan) were investigated by in vivo feeding experiments with [5,5-2H2]-mevalonic acid lactone (d2-MVL) and [5,5-2H2]-1-deoxy-D-xylulose (d2-DOX). The volatiles of the tissues were extracted by stir bar sorptive extraction and analyzed using thermal desorption-multidimensional gas chromatography-mass spectrometry. The experiments demonstrate independent de novo-biosynthesis of terpenoids in carrot roots and in carrot leaves. In both plant tissues monoterpenes are biosynthesized exclusively via the 1-deoxy-D-xylulose/2-C-methyl-D-erythritol-4-phosphate (DOXP/MEP) pathway, whereas sesquiterpenes are generated by the classical mevalonic acid pathway as well as by the DOXP/MEP route. A more detailed investigation of carrot root tissues revealed that the biosynthesis of terpenes is mainly localized in the phloem. Nevertheless, in xylem a de novo-biosynthesis of terpenes was detectable as well, even in the absence of oil ducts in this tissue.
Hampel
Daniela
D
Institut für Lebensmittelchemie, Johann Wolfgang Goethe-Universität, Marie-Curie-Strasse 9, D-60439 Frankfurt/Main, Germany.
Mosandl
Armin
A
Wüst
Matthias
M
D003600:Cytosol / Q000378:metabolism; D018552:Daucus carota / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D004896:Erythritol / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry; D008798:Mevalonic Acid / Q000737:chemistry / Q000378:metabolism*; D039821:Monoterpenes / Q000737:chemistry / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism*; D012717:Sesquiterpenes / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism
D039821:Monoterpenes; D012717:Sesquiterpenes; D004896:Erythritol; D008798:Mevalonic Acid