title: Glutathione deficiency of the Arabidopsis mutant pad2-1 affects oxidative stress-related events, defense gene expression, and the hypersensitive response.
abstract: The Arabidopsis (Arabidopsis thaliana) phytoalexin-deficient mutant pad2-1 displays enhanced susceptibility to a broad range of pathogens and herbivorous insects that correlates with deficiencies in the production of camalexin, indole glucosinolates, and salicylic acid (SA). The pad2-1 mutation is localized in the GLUTAMATE-CYSTEINE LIGASE (GCL) gene encoding the first enzyme of glutathione biosynthesis. While pad2-1 glutathione deficiency is not caused by a decrease in GCL transcripts, analysis of GCL protein level revealed that pad2-1 plants contained only 48% of the wild-type protein amount. In contrast to the wild type, the oxidized form of GCL was dominant in pad2-1, suggesting a distinct redox environment. This finding was corroborated by the expression of GRX1-roGFP2, showing that the cytosolic glutathione redox potential was significantly less negative in pad2-1. Analysis of oxidative stress-related gene expression showed a higher transcript accumulation in pad2-1 of GLUTATHIONE REDUCTASE, GLUTATHIONE-S-TRANSFERASE, and RESPIRATORY BURST OXIDASE HOMOLOG D in response to the oomycete Phytophthora brassicae. Interestingly, oligogalacturonide elicitation in pad2-1 revealed a lower plasma membrane depolarization that was found to act upstream of an impaired hydrogen peroxide production. This impaired hydrogen peroxide production was also observed during pathogen infection and correlated with a reduced hypersensitive response in pad2-1. In addition, a lack of pathogen-triggered expression of the ISOCHORISMATE SYNTHASE1 gene, coding for the SA-biosynthetic enzyme isochorismate synthase, was identified as the cause of the SA deficiency in pad2-1. Together, our results indicate that the pad2-1 mutation is related to a decrease in GCL protein and that the resulting glutathione deficiency negatively affects important processes of disease resistance.
authors: Université de Bourgogne, UMR Plante Microbe Environnement, INRA UMR 1088, CNRS UMR 5184, F-21000 Dijon, France.
authors: Carole
authors: C
authors: Dubreuil-Maurizi
authors: Jan
authors: J
authors: Vitecek
authors: Laurent
authors: L
authors: Marty
authors: Lorelise
authors: L
authors: Branciard
authors: Patrick
authors: P
authors: Frettinger
authors: David
authors: D
authors: Wendehenne
authors: Andreas J
authors: AJ
authors: Meyer
authors: Felix
authors: F
authors: Mauch
authors: Benoît
authors: B
authors: Poinssot
mesh_terms: D000890:Anti-Infective Agents / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000469:parasitology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004198:Disease Susceptibility; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D006861:Hydrogen Peroxide / Q000378:metabolism; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism; D009844:Oligosaccharides / Q000494:pharmacology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010838:Phytophthora / Q000502:physiology*; D010935:Plant Diseases / Q000469:parasitology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000469:parasitology / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D013312:Stress, Physiological
chemical_list: D000890:Anti-Infective Agents; D029681:Arabidopsis Proteins; D009844:Oligosaccharides; D017382:Reactive Oxygen Species; C412763:oligogalacturonic acid; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D020156:Salicylic Acid