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Improved measurements of Na(+) fluxes in plants using calixarene-based microelectrodes.
MedLine Citation:
PMID:  21256620     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Ion-selective microelectrodes are a powerful tool in studying adaptive responses of plant cells and tissues to various abiotic stresses. However, application of this technique in Na(+) flux measurements was limited due to poor selectivity for Na(+) ions of commercially available Na(+) cocktails. Often, these cocktails cannot discriminate between Na(+) and other interfering ions such as K(+) and Ca(2+), leading to inaccurate measurements of Na(+) concentration and, consequently, inaccurate Na(+) flux calculations. To overcome this problem, three Na(+)-selective cocktail mixtures were prepared using tetramethoxyethyl ester derivative of p-t-butyl calix[4]arene. These cocktail mixtures were compared with commercially available ETH 227-based Na(+) cocktail for selectivity for Na(+) ions over other ions (particularly K(+) and Ca(2+)). Among the three calixarene-based Na(+) cocktails tested, cocktail 2 [in % w/w: Na(+) ionophore (4-tert-butylcalix[4]arene-tetra acetic acid tetraethyl ester) 3.5, the plasticizer (2-nitrophenyl octyl ether) 95.9 and lipophilic anion (potassium tetrakis (4-chlorophenyl) borate) 0.6] showed the best selectivity for Na(+) ions over K(+) and Ca(2+) ions and was highly stable over time (up to 10h). Na(+) flux measurements under a wide range of NaCl concentrations (25-150mM) using Na(+) cocktail 2 established a clear dose-response relationship between severity of salt stress and magnitude of Na(+) influx at the distal elongation and mature zones of Arabidopsis thaliana roots. Furthermore, Na(+) cocktail 2 was compared with commercially available ETH 227-based Na(+) cocktail by measuring Na(+) fluxes at the two Arabidopsis root zones in response to 100mM NaCl treatment. With calixarene-based Na(+) cocktail 2, a large decreasing Na(+) influx (0-15min) followed by small Na(+) influx (15-45min) was measured, whereas with ETH-based Na(+) cocktail Na(+) influx was short-lived (1-3min) and was followed by Na(+) efflux (3-45min) that might have been due to K(+) and Ca(2+) efflux measured together with Na(+) influx. In conclusion, Na(+)-selective calixarene-based microelectrodes have excellent potential to be used in real-time Na(+) flux measurements in plants.
Authors:
Maheswari Jayakannan; Olga Babourina; Zed Rengel
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-1-20
Journal Detail:
Title:  Journal of plant physiology     Volume:  -     ISSN:  1618-1328     ISO Abbreviation:  -     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-1-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882059     Medline TA:  J Plant Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier GmbH.
Affiliation:
School of Earth and Environment, The University of Western Australia, M087, Crawley, WA 6009, Perth, Australia.
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