title: Biochemical and physiological processes associated with the differential ozone response in ozone-tolerant and sensitive soybean genotypes.
abstract: Biochemical and physiological traits of two soybean [Glycine max (L.) Merr.] genotypes differing in sensitivity to ozone (O3 ) were investigated to determine the possible basis for the differential response. Fiskeby III (O3 -tolerant) and Mandarin (Ottawa) (O3 -sensitive) were grown in a greenhouse with charcoal-filtered air for 4 weeks, then treated with O3 for 7 h·day(-1) in greenhouse chambers. Mandarin (Ottawa) showed significantly more leaf injury and hydrogen peroxide (H2 O2 ) and superoxide (O2 (-) ) production compared with Fiskeby III. Peroxidase activity in Mandarin (Ottawa) was 31% higher with O3 but was not significantly different in Fiskeby III. Ozone did not affect superoxide dismutase or glutathione reductase activities, or leaf concentrations of glutathione or ascorbic acid. Thus, variation in O3 response between Fiskeby III and Mandarin (Ottawa) was not explained by differences in antioxidant enzymes and metabolites tested. Ethylene emission from leaves declined in Fiskeby III following O3 exposure but not in Mandarin (Ottawa). Ozone exposure reduced quantum yield (ΦPSII ), electron transport rate (ETR) and photochemical quenching (qp ) in Mandarin (Ottawa) more than in Fiskeby III, indicating that efficiency of energy conversion of PSII and photosynthetic electron transport was altered differently in the two genotypes. Short-term exposure to O3 had minimal effects on net carbon exchange rates of both soybean cultivars. A trend toward higher stomatal conductance in Mandarin (Ottawa) suggested stomatal exclusion might contribute to differential O3 sensitivity of the two genotypes. Increased sensitivity of Mandarin (Ottawa) to O3 was associated with higher H2 O2 and O2 (-) production compared with Fiskeby III, possibly associated with genotype differences in stomatal function or regulation of ethylene during the initial phases of O3 response.
authors.affiliation: Department of Agronomy, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Nakhon Pathom, Thailand.
authors.forename: C
authors.initials: C
authors.lastname: Chutteang
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research, and Department of Crop Science, North Carolina State University, Raleigh, NC, USA.
authors.forename: F L
authors.initials: FL
authors.lastname: Booker
authors.affiliation: Sustainability Management Project, Petroleum Authority of Thailand Public Company Limited, Chatuchak, Bangkok, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Na-Ngern
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research, and Department of Crop Science, North Carolina State University, Raleigh, NC, USA.
authors.forename: A
authors.initials: A
authors.lastname: Burton
authors.affiliation: Science Council of Japan, Cabinet Office of Japan, Roppongi, Minato-ku, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Aoki
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Plant Science Research, and Department of Crop Science, North Carolina State University, Raleigh, NC, USA.
authors.forename: K O
authors.initials: KO
authors.lastname: Burkey
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000494:pharmacology; D004579:Electron Transport; D005030:Ethylenes / Q000494:pharmacology; D005838:Genotype; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010126:Ozone / Q000009:adverse effects*; D010788:Photosynthesis / Q000187:drug effects; D010829:Physiological Phenomena / Q000187:drug effects*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018526:Plant Transpiration / Q000187:drug effects*; D013025:Glycine max / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005030:Ethylenes; D010937:Plant Growth Regulators; D010940:Plant Proteins; D010126:Ozone; C036216:ethylene; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione; D001205:Ascorbic Acid
keywords: Antioxidants; ethylene; ozone tolerance; peroxidases; photosynthesis; soybean