title: Beyond toxicity: a regulatory role for mitochondrial cyanide.
abstract: In non-cyanogenic plants, cyanide is a co-product of ethylene and camalexin biosynthesis. To maintain cyanide at non-toxic levels, Arabidopsis plants express the mitochondrial β-cyanoalanine synthase CYS-C1. CYS-C1 knockout leads to an increased level of cyanide in the roots and leaves and a severe defect in root hair morphogenesis, suggesting that cyanide acts as a signaling factor in root development. During compatible and incompatible plant-bacteria interactions, cyanide accumulation and CYS-C1 gene expression are negatively correlated. Moreover, CYS-C1 mutation increases both plant tolerance to biotrophic pathogens and their susceptibility to necrotrophic fungi, indicating that cyanide could stimulate the salicylic acid-dependent signaling pathway of the plant immune system. We hypothesize that CYS-C1 is essential for maintaining non-toxic concentrations of cyanide in the mitochondria to facilitate cyanide's role in signaling.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla; Sevilla, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: García
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla; Sevilla, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Gotor
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla; Sevilla, Spain.
authors.forename: Luis C
authors.initials: LC
authors.lastname: Romero
mesh_terms: D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D003486:Cyanides / Q000378:metabolism*; D008190:Lyases / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology*
chemical_list: D029681:Arabidopsis Proteins; D003486:Cyanides; D008190:Lyases; C019955:beta-cyanoalanine synthase
keywords: cell signaling; cyanide; mitochondria; plant immune response; root hair; β-cyanoalanine synthase