Increased 8-hydroxyguanine content of chloroplast DNA from ozone-treated plants

• Published in: Plant physiology (Bethesda) Vol. 91; no. 2; pp. 644 - 647
• Main Authors: Floyd, R.A. (Oklahoma Medical Research Foundation, Oklahoma City, OK), West, M.S, Hogsett, W.E, Tingey, D.T
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.10.1989
• Subjects: 550200 - Biochemistry; AGENTES NOCIVOS; Agrochemicals products; AMINES; Animal, plant and microbial ecology; Applied ecology; AROMATICS; AZAARENES; BASIC BIOLOGICAL SCIENCES; BIOCHEMICAL REACTION KINETICS; Biological and medical sciences; BIOSINTESIS; BIOSYNTHESE; CELL CONSTITUENTS; Chloroplast DNA; CHLOROPLASTS; DNA; DNA damage; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; ELEMENTS; FACTEUR NUISIBLE; Free radicals; Fundamental and applied biological sciences. Psychology; GUANINA; GUANINE; HETEROCYCLIC COMPOUNDS; HYDROXY COMPOUNDS; Hydroxyl radical clouds; HYDROXYL RADICALS; KINETICS; LEGUMINOSAE; MAGNOLIOPHYTA; MAGNOLIOPSIDA; NONMETALS; NUCLEIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; Other agrochemicals used in plant protection (herbicides, fungicides, etc.); OXIGENO; OXYGEN; OXYGENE; OZONE; OZONO; Peas; PHASEOLUS; PHASEOLUS VULGARIS; Phytopathology. Animal pests. Plant and forest protection; PISUM; PISUM SATIVUM; PLANTS; PLASTE; PLASTIDIOS; Pollution effects and side effects of agrochemicals on crop plants and forest trees. Other anthropogenic factors; Pollution effects. Side effects of agrochemicals; PURINES; RADICALS; REACTION KINETICS; TOXICITY; Oxygen; Hydroxylation; Ozone; Guanine; Free radical; Leguminosae; Vegetable crop; Phaseolus vulgaris; Dicotyledones; DNA; Pisum sativum; Angiospermae; Air pollution; Spermatophyta; Damage; Chloroplast
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.91.2.644

The mechanism of ozone-mediated plant injury is not known but has been postulated to involve oxygen free radicals. Hydroxyl free radicals react with DNA causing formation of many products, one of which is 8-hydroxyguanine. By using high preformance liquid chromatography with electrochemical detection, the 8-hydroxy-2'-deoxyguanosine (8-OHdG) content of a DNA enzymatic digest can be sensitively quantitated. Beans (Phaseolus vulgaris L.) and peas (Pisum sativum L.) were treated with an ozone regime that caused acute injury. Chloroplast DNA was obtained from plants harvested either immediately after ozone treatment or 24 hours later. Ozone-exposed plants in general had nearly two-fold higher levels of 8-OHdG as compared to control plants. In vito treatment of DNA in buffer solution with ozone did not cause formation of 8-OHdG in DNA, even though ozone did react directly with the macromolecule per se. Exposure of isolated, illuminated chloroplasts to ozone caused nearly a seven-fold increase in the amount of 8-OHdG in the chloroplast DNA as compared to none-ozone-exposed chloroplasts. These results suggest that ozone exposure to plants causes formation of enhanced levels of oxygen free radicals, thus mediating formation of 8-OHdG in chloroplast DNA. The reaction of ozone with DNA per se did not cause formation of 8-OHdG. Therefore, it is the interaction of ozone with plant cells and isolated chloroplasts which mediates oxygen free radical formation