PRECIPITATION PROCEDURES FOR SODIUM, POTASSIUM AND CHLORIDE LOCALIZATION IN LEAF-CELLS OF THE HALOPHYTE SUAEDA-MARITIMA

Attempts have been made to localize sodium and potassium with antimonate and cobaltinitrite reagents in Suaeda leaf segments by rapid aqueous and freeze‐substitution precipitation procedures and to localize chloride by freeze‐substitution precipitation with silver ions. Substantial sodium losses occurred from the tissue during both types of preparation although potassium and chloride losses were considerably reduced by the use of freeze‐substitution when compared with the rapid aqueous procedures. The losses during freeze‐substitution resulted from the required use of ethanol as substitution solvent (rather than acetone or diethyl ether, in which the reagents were much less soluble). Analytical electron microscopy showed that silver and cobaltinitrite specifically precipitated chloride and potassium respectively, but antimonate did not specifically precipitate sodium. The vacuoles were important sites of silver and antimonate deposits, although the chloroplasts were the major sites of cobaltinitrite localization. The value of these techniques in ion localization studies is discussed. 1979 Blackwell Science Ltd