Adaptation mechanisms in Rice (Oryza sativa) under salt stress
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)
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.
Rice, Salt stress, Signaling, Tolerance mechanisms
IdentifiersURN: urn:nbn:se:su:diva-19286OAI: oai:DiVA.org:su-19286DiVA: diva2:185810