title: Engineering plant shikimate pathway for production of tocotrienol and improving herbicide resistance.
abstract: Tocochromanols (tocopherols and tocotrienols), collectively known as vitamin E, are essential antioxidant components of both human and animal diets. Because of their potential health benefits, there is a considerable interest in plants with increased or customized vitamin E content. Here, we have explored a new strategy to reach this goal. In plants, phenylalanine is the precursor of a myriad of secondary compounds termed phenylpropanoids. In contrast, much less carbon is incorporated into tyrosine that provides p-hydroxyphenylpyruvate and homogentisate, the aromatic precursors of vitamin E. Therefore, we intended to increase the flux of these two compounds by deriving their synthesis directly at the level of prephenate. This was achieved by the expression of the yeast (Saccharomyces cerevisiae) prephenate dehydrogenase gene in tobacco (Nicotiana tabacum) plants that already overexpress the Arabidopsis p-hydroxyphenylpyruvate dioxygenase coding sequence. A massive accumulation of tocotrienols was observed in leaves. These molecules, which were undetectable in wild-type leaves, became the major forms of vitamin E in the leaves of the transgenic lines. An increased resistance of the transgenic plants toward the herbicidal p-hydroxyphenylpyruvate dioxygenase inhibitor diketonitril was also observed. This work demonstrates that the synthesis of p-hydroxyphenylpyruvate is a limiting step for the accumulation of vitamin E in plants.
authors.affiliation: Laboratoire Mixte Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Bayer CropScience (Unité Mixte de Recherche 1932), 14-20 rue Pierre Baizet, Boite Postale 9163, 69263 Lyon 09, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Rippert
authors.forename: Claire
authors.initials: C
authors.lastname: Scimemi
authors.forename: Manuel
authors.initials: M
authors.lastname: Dubald
authors.forename: Michel
authors.initials: M
authors.lastname: Matringe
mesh_terms: D015111:4-Hydroxyphenylpyruvate Dioxygenase / Q000037:antagonists & inhibitors / Q000235:genetics; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D004274:DNA, Recombinant / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D005800:Genes, Fungal; D017343:Genes, Plant; D005818:Genetic Engineering; D006540:Herbicides / Q000494:pharmacology; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified; D011303:Prephenate Dehydrogenase / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D012765:Shikimic Acid / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism*; D024508:Tocotrienols / Q000378:metabolism*; D014810:Vitamin E / Q000378:metabolism
chemical_list: D004274:DNA, Recombinant; D004791:Enzyme Inhibitors; D006540:Herbicides; D024508:Tocotrienols; D014810:Vitamin E; D012765:Shikimic Acid; D015111:4-Hydroxyphenylpyruvate Dioxygenase; D011303:Prephenate Dehydrogenase