tailieunhanh - Báo cáo khoa học: Assimilation of excess ammonium into amino acids and nitrogen translocation in Arabidopsis thaliana – roles of glutamate synthases and carbamoylphosphate synthetase in leaves

This study was aimed at investigating the physiological role of ferredoxin-glutamate synthases (EC ), NADH-glutamate synthase (EC ) and carbamoylphosphate synthetase (EC ) in Arabidopsis. Pheno-typic analysis revealed a high level of photorespiratory ammonium, gluta-mine⁄glutamate and asparagine⁄aspartate in theGLU1mutant lacking the major ferredoxin-glutamate synthase, indicating that excess photorespiratory ammonium was detoxified into amino acids for transport out of the veins | Assimilation of excess ammonium into amino acids and nitrogen translocation in Arabidopsis thaliana - roles of glutamate synthases and carbamoylphosphate synthetase in leaves Fabien Potel1 Marie-Hélène Valadier1 Sylvie Ferrario-Mery1 Olivier Grandjean2 Halima Morin2 Laure Gaufichon1 Stephanie Boutet-Mercey3 Jeremy Lothier1 Steven J. Rothstein4 Naoya Hirose1 and Akira Suzuki1 1 Unite de Nutrition Azotee des Plantes Institut Nationalde la Recherche Agronomique Versailles France 2 Plateforme de Cytologie et Imagerie Végétale Institut Nationalde la Recherche Agronomique Versailles France 3 Plateforme Chimie du Vegetal Institut Nationalde la Recherche Agronomique Versailles France 4 Department of Molecular and Cellular Biology College of BiologicalScience University of Guelph Ontario Canada Keywords amino acid translocation Arabidopsis thaliana carbamoylphosphate synthetase glutamate synthase nitrogen assimilation Correspondence A. Suzuki Unites de Nutrition Azotee des Plantes Institut Nationalde la Recherche Agronomique Route de St-Cyr 78026 Versailles cedex France Fax 33 1 30 83 30 96 Tel 33 1 30 83 30 87 E-mail suzuki@ Received 27 March 2009 revised 22 May 2009 accepted 27 May 2009 doi This study was aimed at investigating the physiological role of ferredoxin-glutamate synthases EC NADH-glutamate synthase EC and carbamoylphosphate synthetase EC in Arabidopsis. Phenotypic analysis revealed a high level of photorespiratory ammonium gluta-mine glutamate and asparagine aspartate in the GLU1 mutant lacking the major ferredoxin-glutamate synthase indicating that excess photorespiratory ammonium was detoxified into amino acids for transport out of the veins. Consistent with these results promoter analysis and in situ hybridization demonstrated that GLU1 and GLU2 were expressed in the mesophyll and phloem companion cell-sieve element complex. However these phenotypic changes were not detected in the

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