title: Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.
abstract: Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants.
authors.affiliation: Institute of Plant Sciences Paris-Saclay, UMR 9213/UMR1403, CNRS/INRA, Université Paris Sud, Université d'Evry, Université Paris-Diderot, Bâtiment 630, Orsay Cedex, 91405, France.
authors.forename: Younès
authors.initials: Y
authors.lastname: Dellero
authors.affiliation: Institute of Plant Sciences Paris-Saclay, UMR 9213/UMR1403, CNRS/INRA, Université Paris Sud, Université d'Evry, Université Paris-Diderot, Bâtiment 630, Orsay Cedex, 91405, France.
authors.forename: Marlène
authors.initials: M
authors.lastname: Lamothe-Sibold
authors.affiliation: Institute of Plant Sciences Paris-Saclay, UMR 9213/UMR1403, CNRS/INRA, Université Paris Sud, Université d'Evry, Université Paris-Diderot, Bâtiment 630, Orsay Cedex, 91405, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Jossier
authors.affiliation: Institute of Plant Sciences Paris-Saclay, UMR 9213/UMR1403, CNRS/INRA, Université Paris Sud, Université d'Evry, Université Paris-Diderot, Bâtiment 630, Orsay Cedex, 91405, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Hodges
mesh_terms: D000388:Air; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D004579:Electron Transport; D004789:Enzyme Activation; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism*; D000637:Transaminases / Q000235:genetics* / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; C520630:At1g23310 protein, Arabidopsis; D000637:Transaminases; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen
keywords: Arabidopsis thaliana; photorespiration; photosynthesis; primary metabolism; ribulose-1,5-bisphosphate carboxylase/oxygenase; serine.