Nitric oxide mediates root K+/Na+ balance in a mangrove plant, Kandelia obovata, by enhancing the expression of AKT1-type K+ channel and Na+/H+ antiporter under high salinity

• Published in: PloS one Vol. 8; no. 8; p. e71543
• Main Authors: Chen, Juan, Xiong, Duan-Ye, Wang, Wen-Hua, Hu, Wen-Jun, Simon, Martin, Xiao, Qiang, Liu, Ting-Wu, Liu, Xiang, Zheng, Hai-Lei
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 19.08.2013; Public Library of Science (PLoS)
• Subjects: AKT1 protein; Aluminum; Arabidopsis; Arabidopsis thaliana; Biology; Critical components; Cytoplasm; Ecology; Ecosystems; Efflux; Free Radical Scavengers - pharmacology; Gene expression; Gene Expression Regulation, Plant - drug effects; H+-transporting ATPase; Halophytes; Hydrogen; Ion flux; Kandelia obovata; Laboratories; Membrane proteins; Models, Biological; Na+/H+-exchanging ATPase; Na+/K+-exchanging ATPase; Nitric oxide; Nitric Oxide - pharmacology; Nitroprusside - pharmacology; Oryza; Physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - enzymology; Plant Roots - metabolism; Potassium - metabolism; Potassium channels; Potassium Channels - metabolism; Proteins; Proton-Translocating ATPases - metabolism; Puccinellia; Rhizophoraceae - drug effects; Rhizophoraceae - enzymology; Rhizophoraceae - genetics; Rhizophoraceae - metabolism; Roots; Salinity; Salinity effects; Salt tolerance; Salts; Single-nucleotide polymorphism; Sodium; Sodium - metabolism; Sodium Chloride - pharmacology; Sodium nitroprusside; Sodium-Hydrogen Exchangers - metabolism; Synthesis; Transcription, Genetic - drug effects; Wetlands; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0071543

It is well known that nitric oxide (NO) enhances salt tolerance of glycophytes. However, the effect of NO on modulating ionic balance in halophytes is not very clear. This study focuses on the role of NO in mediating K(+)/Na(+) balance in a mangrove species, Kandelia obovata Sheue, Liu and Yong. We first analyzed the effects of sodium nitroprusside (SNP), an NO donor, on ion content and ion flux in the roots of K. obovata under high salinity. The results showed that 100 μM SNP significantly increased K(+) content and Na(+) efflux, but decreased Na(+) content and K(+) efflux. These effects of NO were reversed by specific NO synthesis inhibitor and scavenger, which confirmed the role of NO in retaining K(+) and reducing Na(+) in K. obovata roots. Using western-blot analysis, we found that NO increased the protein expression of plasma membrane (PM) H(+)-ATPase and vacuolar Na(+)/H(+) antiporter, which were crucial proteins for ionic balance. To further clarify the molecular mechanism of NO-modulated K(+)/Na(+) balance, partial cDNA fragments of inward-rectifying K(+) channel, PM Na(+)/H(+) antiporter, PM H(+)-ATPase, vacuolar Na(+)/H(+) antiporter and vacuolar H(+)-ATPase subunit c were isolated. Results of quantitative real-time PCR showed that NO increased the relative expression levels of these genes, while this increase was blocked by NO synthesis inhibitors and scavenger. Above results indicate that NO greatly contribute to K(+)/Na(+) balance in high salinity-treated K. obovata roots, by activating AKT1-type K(+) channel and Na(+)/H(+) antiporter, which are the critical components in K(+)/Na(+) transport system.