Quantitative ion localization within Suaeda maritima leaf mesophyll cells.

Grown under saline conditions, Suaeda maritima accumulates Na(+) and Cl(-) into its leaves, where individual mesophyll cells behave differently in their compartmentation of these ions. Measurements of ion concentrations within selected subcellular compartments show that freeze-substitution with dry sectioning is a valuable preparative technique for analytical electron microscopy of highly vacuolate plant material. Using this approach, absolute estimates were made of Na(+), K(+) and Cl(-) concentrations in the cytoplasm, cell walls, chloroplasts and vacuoles of leaf mesophyll cells.