title: Stress-induced changes in ubiquinone concentration and alternative oxidase in plant mitochondria.
abstract: We have investigated the influence of stress conditions such as incubation at 4 degrees C and incubation in hyperoxygen atmosphere, on plant tissues. The ubiquinone (Q) content and respiratory activity of purified mitochondria was studied. The rate of respiration of mitochondria isolated from cold-treated green bell peppers (Capsicum annuum L) exceeds that of controls, but this is not so for mitochondria isolated from cold-treated cauliflower (Brassica oleracea L). Treatment with high oxygen does not alter respiration rates of cauliflower mitochondria. Analysis of kinetic data relating oxygen uptake with Q reduction in mitochondria isolated from tissue incubated at 4 degrees C (bell peppers and cauliflowers) and at high oxygen levels (cauliflowers) reveals an increase in the total amount of Q and in the percentage of inoxidizable QH2. The effects are not invariably accompanied by an induction of the alternative oxidase (AOX). In those mitochondria where the AOX is induced (cold-treated bell pepper and cauliflower treated with high oxygen) superoxide production is lower than in the control. The role of reduced Q accumulation and AOX induction in the defense against oxidative damage is discussed.
authors.affiliation: Department of Plant Physiology and Biochemistry, Voronezh State University, Russia.
authors.forename: V N
authors.initials: VN
authors.lastname: Popov
authors.forename: A C
authors.initials: AC
authors.lastname: Purvis
authors.forename: V P
authors.initials: VP
authors.lastname: Skulachev
authors.forename: A M
authors.initials: AM
authors.lastname: Wagner
mesh_terms: D001937:Brassica / Q000187:drug effects / Q000378:metabolism*; D002212:Capsicum / Q000187:drug effects / Q000378:metabolism*; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D003080:Cold Temperature / Q000009:adverse effects; D003580:Cytochromes / Q000187:drug effects / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects / Q000502:physiology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010088:Oxidoreductases / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D018521:Plant Physiological Phenomena / Q000187:drug effects*; D010940:Plant Proteins; D013481:Superoxides / Q000378:metabolism; D014451:Ubiquinone / Q000378:metabolism*; D000099188:Alternative Oxidase
chemical_list: D003580:Cytochromes; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010100:Oxygen; D010940:Plant Proteins; D013481:Superoxides; D014451:Ubiquinone; D000099188:Alternative Oxidase