The effect of divalent cations on Na+ tolerance in Charophytes. II: Chara corallina

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Abstract The freshwater Charophyte Chora corallina dies when subjected to 70 molm−3 NaCl if the Ca2+ concentration is 0.1 mol m −3. This stress is accompanied by a depolarization of the cell to a membrane potential more positive than EK, a net influx of Na+ into the vacuole, and a net loss of K+ from the vacuole. Raising the Ca2+ concentration to 7 mol m −3 in the presence of elevated Na+ restores the Na+ to Ca2+ ratio to 10: 1 as in the control solution, and results in enhanced survival even though turgor is not regulated. Mg2+ is not a good substitute for Ca2+. It is suggested that the main reason that C. corallina fails to occupy saline habitats is its failure to regulate turgor, not sensitivity to Na +, since the latter is similar to that seen in C. buckellii, which is found in saline habitats.

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