title: Plant tolerance to excess light energy and photooxidative damage relies on plastoquinone biosynthesis.
abstract: Plastoquinone-9 is known as a photosynthetic electron carrier to which has also been attributed a role in the regulation of gene expression and enzyme activities via its redox state. Here, we show that it acts also as an antioxidant in plant leaves, playing a central photoprotective role. When Arabidopsis plants were suddenly exposed to excess light energy, a rapid consumption of plastoquinone-9 occurred, followed by a progressive increase in concentration during the acclimation phase. By overexpressing the plastoquinone-9 biosynthesis gene SPS1 (solanesyl diphosphate synthase 1) in Arabidopsis, we succeeded in generating plants that specifically accumulate plastoquinone-9 and its derivative plastochromanol-8. The SPS1-overexpressing lines were much more resistant to photooxidative stress than the wild type, showing marked decreases in leaf bleaching, lipid peroxidation and PSII photoinhibition under excess light. Comparison of the SPS1 overexpressors with other prenyl quinone mutants indicated that the enhanced phototolerance of the former plants is directly related to their increased capacities for plastoquinone-9 biosynthesis.
authors.affiliation: CEA, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.|CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, F-13108 Saint-Paul-lez-Durance, France.|Aix-Marseille Université, F-13284 Marseille, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Ksas
authors.affiliation: CEA, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.|CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, F-13108 Saint-Paul-lez-Durance, France.|Aix-Marseille Université, F-13284 Marseille, France.
authors.forename: Noëlle
authors.initials: N
authors.lastname: Becuwe
authors.affiliation: CEA, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.|CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, F-13108 Saint-Paul-lez-Durance, France.|Aix-Marseille Université, F-13284 Marseille, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Chevalier
authors.affiliation: CEA, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.|CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, F-13108 Saint-Paul-lez-Durance, France.|Aix-Marseille Université, F-13284 Marseille, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Havaux
mesh_terms: D000220:Adaptation, Biological; D017360:Arabidopsis / Q000502:physiology / Q000528:radiation effects; D053898:Biosynthetic Pathways; D018506:Gene Expression Regulation, Plant; D008027:Light; D009154:Mutation; D018384:Oxidative Stress; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D018521:Plant Physiological Phenomena; D010971:Plastoquinone / Q000378:metabolism*
chemical_list: D010971:Plastoquinone