Salt stress-induced chloride flux: a study using transgenic Arabidopsis expressing a fluorescent anion probe.
Salt stress leads to massive accumulation of toxic levels of Na(+) and Cl(-) ions in plants. By using the recombinant fluorescent probe CLOMELEON, we demonstrate passive anion flux under salt stress. Chloride influx is restricted in the presence of divalent cations like Mg(2+) and Ca(2+), and completely blocked by La(3+). The amount but not the rate of the reported chloride uptake is independent from the kind of corresponding permeable cation (K(+) versus Na(+)), external pH and magnitude of osmotic stress. Cl(-) efflux however seems to involve stretch-activated transport. From the influence of Ca(2+) on reported changes of cytosolic anion concentrations, we speculate that transport mechanisms of Cl(-) and Na(+) might be thermodynamically coupled under saline conditions.
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Zentrum für Biochemie und Molekularbiologie, Universität Kiel, Am Botanischen Garten 9, 24118 Kiel, Germany.
Aberle
Thomas
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Plieth
Christoph
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D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007811:Lanthanum / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009997:Osmotic Pressure / Q000187:drug effects; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*
D002712:Chlorides; D011993:Recombinant Fusion Proteins; C415371:clomeleon; D012965:Sodium Chloride; D007811:Lanthanum; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium