title: Reassimilation of ammonium in Lotus japonicus.
abstract: This review summarizes the most recent results obtained in the analysis of two important metabolic pathways involved in the release of internal sources of ammonium in the model legume Lotus japonicus: photorespiratory metabolism and asparagine breakdown mediated by aparaginase (NSE). The use of photorespiratory mutants deficient in plastidic glutamine synthetase (GS2) enabled us to investigate the transcriptomics and metabolomic changes associated with photorespiratory ammonium accumulation in this plant. The results obtained indicate the existence of a coordinate regulation of genes involved in photorespiratory metabolism. Other types of evidence illustrate the multiple interconnections existing among the photorespiratory pathway and other processes such as intermediate metabolism, nodule function, and secondary metabolism in this plant, all of which are substantially affected in GS2-deficient mutants because of the impairment of the photorespiratory cycle. Finally, the importance of asparagine metabolism in L. japonicus is highlighted because of the fact that asparagine constitutes the vast majority of the reduced nitrogen translocated between different organs of this plant. The different types of NSE enzymes and genes which are present in L. japonicus are described. There is a particular focus on the most abundant K(+)-dependent LjNSE1 isoform and how TILLING mutants were used to demonstrate by reverse genetics the importance of this particular isoform in plant growth and seed production.
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: Marco
authors.initials: M
authors.lastname: Betti
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: Margarita
authors.initials: M
authors.lastname: García-Calderón
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Pérez-Delgado
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Credali
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P.J. Šafárik University, Mánesova 23, SK-04001 Košice, Slovak Republic.
authors.forename: Peter
authors.initials: P
authors.lastname: Pal'ove-Balang
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Estivill
authors.affiliation: Institute of Biology and Ecology, Faculty of Science, P.J. Šafárik University, Mánesova 23, SK-04001 Košice, Slovak Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Repčák
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Vega
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Galván
authors.affiliation: Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Química, C/ Profesor García González, 1, 41012-Sevilla, Spain cabeza@us.es.
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Márquez
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D001216:Asparagine / Q000378:metabolism*; D001692:Biological Transport; D019069:Cell Respiration; D018506:Gene Expression Regulation, Plant; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D008027:Light; D000070116:Lotus / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D015394:Molecular Structure; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism*; D018087:Plastids / Q000201:enzymology; D011188:Potassium / Q000378:metabolism; D059386:Reverse Genetics; D012639:Seeds / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D059467:Transcriptome
chemical_list: D064751:Ammonium Compounds; D001216:Asparagine; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen; D011188:Potassium
keywords: Asparaginase; asparagine; glutamine synthetase; mutants; photorespiratory metabolism; transcriptomics.