title: Benzothiadiazole inhibits mitochondrial NADH:ubiquinone oxidoreductase in tobacco.
abstract: An inducer of acquired disease resistance in plants, benzo (1,2,3) thiadiazole-7-carbothioic acid S-methyl ester, exhibited direct, concentration-dependent inhibition of the NADH:ubiquinone oxidoreductase activity of complex I of the mitochondrial electron transport chain of cultured tobacco cells. The complex I activity was less sensitive to inhibition by salicylic acid, an endogenous activator of acquired disease resistance. Using a dichlorodihydrofluorescein assay, it was found that benzothiadiazole, salicylic acid and the complex I inhibitor rotenone, increased reactive oxygen species production within cells in a concentration-dependent manner. The results indicate that both benzothiadiazole and salicylic acid affect the mitochondria of treated plant cells and result in increased production of reactive oxygen species. The biochemical basis of this response could be related to the inhibition of the NADH:ubiquinone oxidoreductase activity of complex I that results in channelling of electrons via complex II, with concomitant higher levels of superoxide production.
authors.affiliation: Department of Biochemistry, University of Johannesburg, Kingsway Campus, P.O. Box 524, Auckland Park 2006, South Africa.
authors.forename: Johannes A
authors.initials: JA
authors.lastname: van der Merwe
authors.forename: Ian A
authors.initials: IA
authors.lastname: Dubery
mesh_terms: D002478:Cells, Cultured; D004579:Electron Transport / Q000187:drug effects; D042967:Electron Transport Complex I / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010940:Plant Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology; D020156:Salicylic Acid / Q000494:pharmacology; D013830:Thiadiazoles / Q000494:pharmacology*; D014026:Nicotiana / Q000187:drug effects* / Q000201:enzymology
chemical_list: D024101:Mitochondrial Proteins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013830:Thiadiazoles; D012402:Rotenone; C015700:benzo-1,2,3-thiadiazole; D042967:Electron Transport Complex I; D020156:Salicylic Acid