title: The two senescence-related markers, GS1 (cytosolic glutamine synthetase) and GDH (glutamate dehydrogenase), involved in nitrogen mobilization, are differentially regulated during pathogen attack and by stress hormones and reactive oxygen species in Nicotiana tabacum L. leaves.
abstract: To investigate the role of stress in nitrogen management in plants, the effect of pathogen attack, elicitors, and phytohormone application on the expression of the two senescence-related markers GS1 (cytosolic glutamine synthetase EC 6.3.1.2) and GDH (glutamate dehydrogenase, EC 1.4.1.2) involved in nitrogen mobilization in senescing leaves of tobacco (Nicotiana tabacum L.) plants, was studied. The expression of genes involved in primary nitrogen assimilation such as GS2 (chloroplastic glutamine synthetase) and Nia (nitrate reductase, EC 1.6.1.1) was also analysed. The Glubas gene, coding a beta-1,3-glucanase, was used as a plant-defence gene control. As during natural senescence, the expression of GS2 and Nia was repressed under almost all stress conditions. By contrast, GS1 and GDH mRNA accumulation was increased. However, GS1 and GDH showed differential patterns of expression depending on the stress applied. The expression of GS1 appeared more selective than GDH. Results indicate that the GDH and GS1 genes involved in leaf senescence are also a component of the plant defence response during plant-pathogen interaction. The links between natural plant senescence and stress-induced senescence are discussed, as well as the potential role of GS1 and GDH in a metabolic safeguard process.
authors.affiliation: INRA Unité de Nutrition Azotée des Plantes, Route de Saint Cyr, F-78 026 Versailles Cedex, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Pageau
authors.forename: Michèle
authors.initials: M
authors.lastname: Reisdorf-Cren
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Morot-Gaudry
authors.forename: Céline
authors.initials: C
authors.lastname: Masclaux-Daubresse
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D017799:Cucumovirus / Q000472:pathogenicity; D003517:Cyclopentanes / Q000494:pharmacology; D005030:Ethylenes / Q000494:pharmacology; D005658:Fungi / Q000472:pathogenicity; D018506:Gene Expression Regulation, Plant; D005969:Glutamate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D018384:Oxidative Stress; D054883:Oxylipins; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017800:Potyvirus / Q000472:pathogenicity; D011549:Pseudomonas / Q000472:pathogenicity; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020156:Salicylic Acid / Q000494:pharmacology; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology* / Q000382:microbiology
chemical_list: D015415:Biomarkers; D003517:Cyclopentanes; D005030:Ethylenes; D054883:Oxylipins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; C011006:jasmonic acid; C036216:ethylene; D005969:Glutamate Dehydrogenase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen; D020156:Salicylic Acid