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Adaptation mechanisms in Rice (Oryza sativa) under salt stress
Stockholm University, Faculty of Science, Department of Botany. växtfysiologi. (Sylvia Lindberg)
Stockholm University, Faculty of Science, Department of Botany. växtfysiologi. (Sylvia lindberg)
2007 (English)In: 2nd World Conference on Stress: 3rd Cell Stress Society International Congress on Stress Responses in Biology and Mediin, 2007, 1- p.Conference paper (Refereed)
Abstract [en]

The project focuses on two important aspects of Na+ toxicity in salt-tolerant rice cv. Pokkali and salt-sensitive cv. BRRI Dhan29, namely i) how Na+ stress induces a change in cytosolic Ca2+, [Ca2+]cyt, and pH, [pH]cyt, and ii) how cells could maintain a low cytosolic Na+ and/or Na+/K+ ratio. The salt-induced changes in [Ca2+]cyt and [pH]cyt and their sources were monitored in single rice protoplasts by fluorescence microscopy. The expression of the transporter genes OsHKT1, OsHKT2 and OsVHA, which are thought to play a significant role in maintaining correct cytosolic Na+ and or Na+/K+ ratio, were examined in both rice cultivars under salt stress condition by real time RT-PCR and in situ PCR. The results show that Na+ must be sensed inside the cytosol, before any changes in [Ca2+]cyt and [pH]cyt occur. Sensing of Na+ induced different changes in [Ca2+]cyt and [pH]cyt in the two rice cultivars with different sources for the changes. The [pH]cyt changes were coupled to different

H+-ATPases in the two cultivars. The expression analysis of OsHKT1, OsHKT2 and OsVHA showed variable and cell- specific induction in these cultivars under salt stress condition. The important mechanism for salt tolerance in cv. Pokkali was to keep cytosolic Na+ at a low level, by reducing Na+-influx (through down-regulation of OsHKT1) and compartmentalizing cytosolic Na+ into the vacuole (through the induction of vacuolar H+ATPase OsVHA, an energizer for the tonoplast Na+/H+ antiporter). Pokkali might also induce increased uptake of K+ through the induction of OsHKT2, as evident in this study. Vacuolar

compartmentalization of Na+ is also present in salt-sensitive cv. BRRI Dhan29, but to a lesser extent and much later than in cv. Pokkali. The results suggest that the signaling and subsequent adaptive responses in the salt-tolerant rice cv. Pokkali are different from that in the salt-sensitive cv. BRRI Dhan29.

Place, publisher, year, edition, pages
2007. 1- p.
Keyword [en]
Rice, Salt stress, Signaling, Tolerance mechanisms
National Category
URN: urn:nbn:se:su:diva-19286OAI: diva2:185810
Available from: 2007-11-01 Created: 2007-11-01Bibliographically approved

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