Enhanced tolerance to salt stress in transgenic rice that overexpresses chloroplast glutamine synthetase

• Published in: Plant molecular biology Vol. 43; no. 1; pp. 103 - 111
• Main Authors: Hoshida, H, Tanaka, Y, Hibino, T, Hayashi, Y, Tanaka, A, Takabe, T
• Format: Journal Article
• Language: English
• Published: Netherlands Springer Nature B.V 01.05.2000
• Subjects: Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Carbon Dioxide - metabolism; Carbon Dioxide - pharmacology; Chloroplasts - enzymology; Cold Temperature; Crop science; Electron Transport - drug effects; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Glutamate-Ammonia Ligase - genetics; Glutamate-Ammonia Ligase - metabolism; glutamine synthase; Isoniazid - pharmacology; Oryza - drug effects; Oryza - genetics; Oryza - physiology; Oryza sativa; Photosynthesis - drug effects; Plant Leaves - metabolism; Plants, Genetically Modified - drug effects; Plants, Genetically Modified - genetics; Plants, Genetically Modified - physiology; Quaternary Ammonium Compounds - analysis; Rice; salt stress; Salt tolerance; Sodium - analysis; Sodium chloride; Sodium Chloride - pharmacology; Transgenic plants
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1006408712416

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.