Heterologous expression of vacuolar H+-PPase enhances the electrochemical gradient across the vacuolar membrane and improves tobacco cell salt tolerance |
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Authors: | Xiao-Guang Duan Ai-Fang Yang Feng Gao Shang-Li Zhang Ju-Ren Zhang |
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Institution: | (1) School of Life Science, Shandong University, Jinan |
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Abstract: | Summary. The vacuolar H+-translocating inorganic pyrophosphatase (H+-PPase) uses pyrophosphate as substrate to generate the proton electrochemical gradient across the vacuolar membrane to acidify
vacuoles in plant cells. The heterologous expression of H+-PPase genes (TsVP from Thellungiella halophila and AVP1 from Arabidopsis thaliana) improved the salt tolerance of tobacco plants. Under salt stress, the transgenic seedlings showed much better growth and
greater fresh weight than wild-type plants, and their protoplasts had a normal appearance and greater vigor. The cytoplasmic
and vacuolar pH in transgenic and wild-type cells were measured with a pH-sensitive fluorescence indicator. The results showed
that heterologous expression of H+-PPase produced an enhanced proton electrochemical gradient across the vacuolar membrane, which accelerated the sequestration
of sodium ions into the vacuole. More Na+ accumulated in the vacuoles of transgenic cells under salt (NaCl) stress, revealed by staining with the fluorescent indicator
Sodium Green. It was concluded that the tonoplast-resident H+-PPase plays important roles in the maintenance of the proton gradient across the vacuolar membrane and the compartmentation
of Na+ within vacuoles, and heterologous expression of this protein enhanced the electrochemical gradient across the vacuolar membrane,
thereby improving the salt tolerance of tobacco cells.
Correspondence: J.-R. Zhang, School of Life Science, Shandong University, 27 Shanda South Road, Jinan, People’s Republic of
China 250100. |
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Keywords: | : H+-PPase Cytoplasmic pH Vacuolar pH Vacuolar membrane potential Salt tolerance Nicotiana tabacum |
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