title: Enhanced tolerance to salt stress in transgenic rice that overexpresses chloroplast glutamine synthetase.
abstract: The potential role of photorespiration in the protection against salt stress was examined with transgenic rice plants. Oryza sativa L. cv. Kinuhikari was transformed with a chloroplastic glutamine synthetase (GS2) gene from rice. Each transgenic rice plant line showed a different accumulation level of GS2. A transgenic plant line, G39-2, which accumulated about 1.5-fold more GS2 than the control plant, had an increased photorespiration capacity. In another line, G241-12, GS2 was almost lost and photorespiration activity could not be detected. Fluorescence quenching analysis revealed that photorespiration could prevent the over-reduction of electron transport systems. When exposed to 150 mM NaCl for 2 weeks, the control rice plants completely lost photosystem II activity, but G39-2 plants retained more than 90% activity after the 2-week treatment, whereas G241-12 plants lost these activities within one week. In the presence of isonicotinic acid hydrazide, an inhibitor of photorespiration, G39-2 showed the same salt tolerance as the control plants. The intracellular contents of NH4+ and Na+ in the stressed plants correlated well with the levels of GS2. Thus, the enhancement of photorespiration conferred resistance to salt in rice plants. Preliminary results suggest chilling tolerance in the transformant.
authors.affiliation: Research Institute, Meijo University, Nagoya, Aichi, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Hoshida
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Hibino
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashi
authors.forename: A
authors.initials: A
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Takabe
authors.forename: T
authors.initials: T
authors.lastname: Takabe
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology; D002736:Chloroplasts / Q000201:enzymology*; D003080:Cold Temperature; D004579:Electron Transport / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005974:Glutamate-Ammonia Ligase / Q000235:genetics* / Q000378:metabolism; D007538:Isoniazid / Q000494:pharmacology; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012964:Sodium / Q000032:analysis; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D000644:Quaternary Ammonium Compounds; D002245:Carbon Dioxide; D012965:Sodium Chloride; D012964:Sodium; D005974:Glutamate-Ammonia Ligase; D007538:Isoniazid