title: Cellular proton dynamics in Elodea canadensis leaves induced by cadmium.
abstract: Our earlier investigations showed that Elodea canadensis shoots, grown in the presence of cadmium (Cd), caused basification of the surrounding medium. The present study was aimed to examine the proton dynamics of the apoplastic, cytosolic and vacuolar regions of E. canadensis leaves upon Cd exposure and to establish possible linkage between cellular pH changes and the medium basification. The changes in cytosolic calcium [Ca(2+)]cyt was also investigated as the [Ca(2+)]cyt and [pH]cyt homeostasis are closely linked. The cellular H(+) and Ca(2+) concentrations were monitored by fluorescence microscopy and ion-specific fluorescent dyes. Cadmium concentration of leaf-cell walls was measured after plant cultivation at different fixed levels of starting pH. The protoplasts from E. canadensis leaves were isolated by use of a newly developed enzymatic method. Upon Cd addition, both cytosolic and vacuolar pH of leaf protoplasts increased with a concomitant rise in the cytosolic Ca(2+) concentration. Time course studies revealed that changes in [Ca(2+)]cyt and [pH]cyt followed similar dynamics. Cadmium (0.5 μM) exposure decreased the apoplastic pH by 0.85 units. The maximum cell wall bound Cd-contents were obtained in plants grown at low starting pH. It is concluded that Cd treatment causes apoplastic acidosis in E. canadensis leaves associated with enhanced Cd binding to the cell walls and, consequently, reduced Cd influx into the cytosol.
authors: Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 Stockholm, Sweden. Electronic address: mtariqjaved@gcuf.edu.pk.
authors: M
authors: M
authors: Tariq Javed
authors: Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 Stockholm, Sweden.
authors: Sylvia
authors: S
authors: Lindberg
authors: Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 Stockholm, Sweden.
authors: Maria
authors: M
authors: Greger
mesh_terms: D002104:Cadmium / Q000009:adverse effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism; D031321:Hydrocharitaceae / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D059828:Plant Cells / Q000187:drug effects* / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011522:Protons; D011523:Protoplasts / Q000187:drug effects / Q000378:metabolism; D013312:Stress, Physiological; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism
chemical_list: D011522:Protons; D002104:Cadmium; D002118:Calcium
keywords: Apoplastic pH; Cadmium; Cytosolic Ca(2+); Cytosolic pH; Proton dynamics; Protoplast; Vacuolar pH