title: Transient transcriptional regulation of the CYS-C1 gene and cyanide accumulation upon pathogen infection in the plant immune response.
abstract: Cyanide is produced concomitantly with ethylene biosynthesis. Arabidopsis (Arabidopsis thaliana) detoxifies cyanide primarily through the enzyme β-cyanoalanine synthase, mainly by the mitochondrial CYS-C1. CYS-C1 loss of function is not toxic for the plant and leads to an increased level of cyanide in cys-c1 mutants as well as a root hairless phenotype. The classification of genes differentially expressed in cys-c1 and wild-type plants reveals that the high endogenous cyanide content of the cys-c1 mutant is correlated with the biotic stress response. Cyanide accumulation and CYS-C1 gene expression are negatively correlated during compatible and incompatible plant-bacteria interactions. In addition, cys-c1 plants present an increased susceptibility to the necrotrophic fungus Botrytis cinerea and an increased tolerance to the biotrophic Pseudomonas syringae pv tomato DC3000 bacterium and Beet curly top virus. The cys-c1 mutation produces a reduction in respiration rate in leaves, an accumulation of reactive oxygen species, and an induction of the alternative oxidase AOX1a and pathogenesis-related PR1 expression. We hypothesize that cyanide, which is transiently accumulated during avirulent bacterial infection and constitutively accumulated in the cys-c1 mutant, uncouples the respiratory electron chain dependent on the cytochrome c oxidase, and this uncoupling induces the alternative oxidase activity and the accumulation of reactive oxygen species, which act by stimulating the salicylic acid-dependent signaling pathway of the plant immune system.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, E-41092 Seville, Spain. irene.garcia@ibvf.csic.es
authors.forename: Irene
authors.initials: I
authors.lastname: García
authors.forename: Tábata
authors.initials: T
authors.lastname: Rosas
authors.forename: Eduardo R
authors.initials: ER
authors.lastname: Bejarano
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gotor
authors.forename: Luis C
authors.initials: LC
authors.lastname: Romero
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000382:microbiology / Q000821:virology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D020171:Botrytis / Q000472:pathogenicity; D003486:Cyanides / Q000378:metabolism*; D003547:Cysteine Synthase / Q000235:genetics* / Q000378:metabolism; D060467:Disease Resistance; D017791:Geminiviridae / Q000472:pathogenicity; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology*; D006879:Hydroxocobalamin / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000821:virology; D057865:Plant Immunity / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics; D044224:Pseudomonas syringae / Q000472:pathogenicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000099188:Alternative Oxidase
chemical_list: D029681:Arabidopsis Proteins; D003486:Cyanides; D003547:Cysteine Synthase; D006879:Hydroxocobalamin; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D000099188:Alternative Oxidase; C077262:PR-1 protein, Arabidopsis; C587578:CYS-C1 protein, Arabidopsis