Cellular traits for sodium tolerance in rice (Oryza sativa L.)
2008 (English)In: Plant Biotechnology, ISSN 0289577, Vol. 25, no 3, 247-255 p.Article in journal (Refereed) Published
The present review focuses on two important aspects of Na+ toxicity in rice (Oryza sativa L.), i) that Na+ stress induces different changes in cytosolic Ca2+, [Ca2+]cyt, and pH, [pH]cyt, in tolerant and sensitive cultivars, and ii) that cells from a tolerant cultivar can better maintain a low cytosolic Na+ and/or Na+/K+ ratio. Experiments with single rice protoplasts, fluorescence microscopy and specific ion-selective dyes suggest that Na+ must be sensed inside the cytosol, before any prolonged changes in [Ca2+]cyt and [pH]cyt occur. Inhibitor analyses show that Na+-induced increase in [pH]cyt in the tolerant cv. Pokkali, and a decrease in [pH]cyt in the sensitive cv. BRRI DHan29, likely are coupled to different H+-ATPases. Expression analysis of OsHKT2;1 (previous name OsHKT1), OsHKT2;2 (previous name OsHKT2) and OsVHA transcripts in rice using RT-PCR and fluorescence in situ-PCR, shows a variable and cell- specific induction in the two rice cultivars under salt stress condition. We conclude that the transient uptake of Na+, which occurs only in the tolerant cultivar, and the fast compartmentalization of Na+ into the vacuole, probably are the most important cellular traits for Na+-tolerance in rice. The low [Na+]cyt in cv. Pokkali might depend on the fast down-regulation of OsHKT2;1, causing less uptake of Na+, and fast up-regulation of the OsVHA transcript, and subsequent activation of the Na+/H+-anti-porter in the tonoplast. To decrease the cytosolic Na+/K+ ratio under Na+ toxicity, cv. Pokkali may also induce increased uptake of K+ through induction of OsHKT2;2, and other specific K+-transporter genes.
Place, publisher, year, edition, pages
2008. Vol. 25, no 3, 247-255 p.
Cytosolic calcium and pH, H+ATPase, HKT, Na-toxicity, Oryza sativa
IdentifiersURN: urn:nbn:se:su:diva-15293ISI: 000262639800008OAI: oai:DiVA.org:su-15293DiVA: diva2:181813
Projekt A. In the program:Plasma membrane properties and signal transduction in plant cells under stress