Plant and Cell Physiology Advance Access originally published online on April 17, 2008
Plant and Cell Physiology 2008 49(6):880-890; doi:10.1093/pcp/pcn062
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Overexpression of a New Rice Vacuolar Antiporter Regulating Protein OsARP Improves Salt Tolerance in Tobacco
1Laboratory of Plant Biotechnology, The United Graduate School of Agricultural Sciences, Tottori University, Koyama-cho, Minami 4-101, Tottori 680-8553, Japan
2The State Key Laboratory of Plant Physiology and Biochemistry, College of Life Science, Zhejiang University, Hangzhou 310058, PR China
3Laboratory of Plant Nutrition, The United Graduate School of Agricultural Sciences, Tottori University, Koyama-cho, Minami 4-101, Tottori 680-8553, Japan
4Department of Veterinary Physiology, Faculty of Veterinary Medicine, Tottori University, Koyama-cho, Minami 4-101, Tottori 680-8553, Japan
5The State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling, Shaanxi 712100, PR China
6Laboratory of Environmental Biotechnology, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon 305-806, Korea
*Corresponding author: E-mail, jotanaka{at}muses.tottori-u.ac.jp; Fax, +81-857-31-5638.
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Abstract |
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We examined the function of the rice (Oryza sativa L.) antiporter-regulating protein OsARP by overexpressing it in tobacco (Nicotiana tabacum L.). In public databases, this protein was annotated as a putative Os02g0465900 protein of rice. The OsARP gene was introduced into tobacco under the control of the cauliflower mosaic virus 35S promoter. The transformants were selected for their ability to grow on medium containing kanamycin. Incorporation of the transgene in the genome of tobacco was confirmed by PCR, and its expression was confirmed by Western blot analysis. Transgenic plants had better growth and vigor than non-transgenic plants under salt stress in vitro. Overexpression of OsARP in transgenic tobacco plants resulted in salt tolerance, and the plants had a higher rate of photosynthesis and effective PSII photon yield when compared with the wild type. The OsARP protein was localized in the tonoplast of rice plants. Transgenic plants accumulated more Na+ in their leaf tissue than did wild-type plants. It is conceivable that the toxic effect of Na+ in the cytosol might be reduced by sequestration into vacuoles. The rate of water loss was higher in the wild type than in transgenic plants under salt stress. Increased vacuolar solute accumulation and water retention could confer salt tolerance in transgenic plants. Tonoplast vesicles isolated from OsARP transgenic plants showed Na+/H+ exchange rates 3-fold higher than those of wild-type plants. These results suggest that OsARP on the tonoplasts plays an important role in compartmentation of Na+ into vacuoles. We suggest that OsARP is a new type of protein participating in Na+ uptake in vacuoles.
Keywords: Na+/H+ exchange - Rice (Oryza sativa L.) - Salt tolerance - Tobacco (Nicotiana tabacum L.) - Vacuolar antiporter regulator
Abbreviations: BSA, bovine serum albumin; BTP, 1,3-bis[tris(hydroxymethyl) methylamino]propane; DTT, dithiothreitol; EGTA, ethylene glycol-bis(β-aminoethylether)-N,N,N',N'-tetraacetic acid; IPTG, isopropyl-β-D-thiogalactopyranoside; MS, Murashige–Skoog; PBS, phosphate-buffered saline; PVP, polyvinylpyrrolidone.
(Received April 8, 2008; Accepted April 13, 2008)
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