Anoxia and Oxidative Stress: Lipid Peroxidation, Antioxidant Status and Mitochondrial Functions in Plants

Front cover: Flowering Iris germanica (upper picture) and Iris pseudacorus. Corresponding electron micrographs show the formation of hydrogen peroxide under hypoxia on the plasma membrane and in the cell wall. ABBREVIATIONS AA ascorbic acid ADH alcohol dehydrogenase ANP anaerobically induced proteins CD conjugated dienes CT conjugated rienes CsA cyclosporin A DHA dehydroascorbic acid DHAR dehydroascorbate reductase DNP dinitrophenol ETC electron transport chain GR glutathione reductase GSH reduced glutathione GSSG glutathione disulphide HIF1 hypoxia−inducible factor1 FCCP p-trifluoro-metoxyphenylhydr-azone LDH lactate dehydrogenase LP lipid peroxidation MDA malon dialdehyde MDHA monodehydro-ascorbic acid MDHAR monodehydro-ascorbate-reductase MS mass spectrometry NEM N-ethyl-maleimide PDC pyruvate decarboxylase Pi inorganic phosphorus PTP permeability transition pore PUFA polyunsaturated fatty acid PUFA−O • lipid alkoxyl radical PUFA−OO • lipid peroxyl radical PUFA−OOH lipid hydroperoxide ROS reactive oxygen species SD second derivative SOD superoxide dismutase TBARS thiobarbituric acid reactive substances TLC thin layer chromatography TOH reduced tocopherol XO xanthine oxidase ORIGINAL PUBLICATIONS This thesis is based on the following original publications, which will be referred to in the text by their Roman numerals. peroxidation and antioxidant systems under anoxia in plants differing in their tolerance to oxygen deficiency. Russ. between lipid peroxidation and anoxia tolerance in a range of species during post-anoxic reaeration. Physiol. Plantarum 105(4): 625-632. SUMMARY Research on the formation of reactive oxygen species (ROS) and the consequences in the cell under anoxia is of great importance in the elucidation of essential questions in stress physiology. Oxygen deprivation stress, and particularly transient hypoxia, has been suggested recently as a convenient model for the investigation of O 2 /ROS sensing. Hence, it is of importance to show direct ROS formation under oxygen deprivation in plant tissues with respect to anoxia tolerance. Another problem, which is of great practical importance, includes physiological processes underlying anoxia tolerance. In the present study emphasis has been placed on the differences between anoxia-tolerant (Iris pseudacorus, Oryza sativa or Ovena sativa) and anoxia-intolerant (Iris germanica, Triticum aestivum) plant species in ROS production, development of lipid peroxidation (LP) during propagation and termination phases and antioxidant status of the cells under anoxic stress. In addition, the consequences of re-admission of oxygen (reoxygenation injury) have been studied. The above mentioned parameters can be affected by the metabolic changes brought about by anoxic stress: a decrease in adenylate energy charge, acidification of cytoplasm, elevation of cytosolic Ca 2+ concentration, changes in the redox state and alterations in membrane structure and functions. Possible …