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Effects of salinity and turgor on calcium influx in Chara
Author(s) -
REID R. J.,
TESTER M.,
SMITH F. A.
Publication year - 1993
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1993.tb00902.x
Subject(s) - turgor pressure , biophysics , calcium , chara , mannitol , chemistry , vacuole , salinity , sodium , botany , biochemistry , biology , cytoplasm , ecology , organic chemistry
Measurements were made of the influx of 45 Ca into internodal cells of Chara corallina in solutions containing high concentrations of NaCl. Increasing salinity in the range 4–100mol m −3 NaCl resulted in a doubling of Ca 2+ influx at the plasmalemma. A time‐course of Ca 2+ influx in 50 mol m −3 NaCl, 0.5mol m −3 CaCl 2 showed that while influx at the plasmalemma increased only 1.5‐fold, influx to the vacuole increased by up to 15‐fold. This was interpreted as being due to inhibition of active Ca 2+ efflux from the cell. The stimulation of Ca 2+ influx by increasing salinity appeared to be principally a response to reduced turgor since similar stimulations were obtained when turgor was reduced by NaCl, Na 2 SO 4 or mannitol. When cells were plasmolysed Ca 2+ influx increased by 10–20‐fold. The increased permeability was relatively specific for Ca 2+ and was inhibitable by La 3+ . Survival of cells in high salt conditions was increased by 30 mmol m −3 La 3+ , which inhibited Ca 2+ influx. Paradoxically, survival can also be extended by increasing external Ca 2+ which leads to a higher influx. Therefore, it seems unlikely that the ameliorative effect of Ca 2+ on the sensitivity of plants to high NaCl is mediated by Ca 2+ entry across the plasmalemma. It seems more likely that the principal role of Ca 2+ under these conditions is exerted externally through the control of membrane voltage and permeability.