Dubreuil-Maurizi, Carole Vitecek, Jan Marty, Laurent Branciard, Lorelise Frettinger, Patrick Wendehenne, David Meyer, Andreas J. Mauch, Felix Poinssot, Benoît 2011-10-17 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. application/pdf https://folia.unifr.ch/global/documents/302358 https://folia.unifr.ch/documents/302358/files/mau_gda.pdf https://folia.unifr.ch/documents/302358/files/mau_gda_sm.pdf eng http://dx.doi.org/10.​1104/​pp.​111.​182667 info:eu-repo/semantics/openAccess License undefined Plant Physiology. - 2011, vol. 157, no. 4, p. 2000-2012 info:eu-repo/classification/udc/57 Glutathione deficiency of the Arabidopsis mutant pad2-1 affects oxidative stress-related events, defense gene expression, and the hypersensitive response http://purl.org/coar/resource_type/c_6501