title: Decreased glycolate oxidase activity leads to altered carbon allocation and leaf senescence after a transfer from high CO2 to ambient air in Arabidopsis thaliana.
abstract: Metabolic and physiological analyses of Arabidopsis thaliana glycolate oxidase (GOX) mutant leaves were performed to understand the development of the photorespiratory phenotype after transfer from high CO2 to air. We show that two Arabidopsis genes, GOX1 and GOX2, share a redundant photorespiratory role. Air-grown single gox1 and gox2 mutants grew normally and no significant differences in leaf metabolic levels and photosynthetic activities were found when compared with wild-type plants. To study the impact of a highly reduced GOX activity on plant metabolism, both GOX1 and GOX2 expression was knocked-down using an artificial miRNA strategy. Air-grown amiRgox1/2 plants with a residual 5% GOX activity exhibited a severe growth phenotype. When high-CO2-grown adult plants were transferred to air, the photosynthetic activity of amiRgox1/2 was rapidly reduced to 50% of control levels, and a high non-photochemical chlorophyll fluorescence quenching was maintained. (13)C-labeling revealed that daily assimilated carbon accumulated in glycolate, leading to reduced carbon allocation to sugars, organic acids, and amino acids. Such changes were not always mirrored in leaf total metabolite levels, since many soluble amino acids increased after transfer, while total soluble protein, RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), and chlorophyll amounts decreased in amiRgox1/2 plants. The senescence marker, SAG12, was induced only in amiRgox1/2 rosettes after transfer to air. The expression of maize photorespiratory GOX in amiRgox1/2 abolished all observed phenotypes. The results indicate that the inhibition of the photorespiratory cycle negatively impacts photosynthesis, alters carbon allocation, and leads to early senescence in old rosette leaves.
authors.affiliation: Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, INRA, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France.
authors.forename: Younès
authors.initials: Y
authors.lastname: Dellero
authors.affiliation: Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, INRA, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Jossier
authors.affiliation: Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, INRA, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Glab
authors.affiliation: Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, INRA, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Oury
authors.affiliation: Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, INRA, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tcherkez
authors.affiliation: Institute of Plant Sciences Paris-Saclay, CNRS, Université Paris-Sud, INRA, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, 91405 Orsay Cedex, France michael.hodges@u-psud.fr.
authors.forename: Michael
authors.initials: M
authors.lastname: Hodges
mesh_terms: D000375:Aging / Q000378:metabolism / Q000502:physiology; D000429:Alcohol Oxidoreductases / Q000378:metabolism* / Q000502:physiology; D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D002734:Chlorophyll; D002245:Carbon Dioxide; D000429:Alcohol Oxidoreductases; C578060:Gox1 protein, Arabidopsis; C578061:Gox3 protein, Arabidopsis; C020821:glycollate oxidase
keywords: Arabidopsis; carbon allocation; mutant; photorespiration; photosynthesis; senescence.