Determination of inorganic cations and anions in single plant cells by capillary zone electrophoresis

Investigation of the solute transport in plants on a molecular level requires the knowledge of the solute distribution between different cells within a tissue. Capillary electrophoresis is demonstrated as a useful technique for the determination of a number of solutes in single plant cell vacuoles. The procedures of sampling vacuolar sap, dilution of the sample, internal standardization and subsequent injection into the separation capillary are described. Extracted vacuolar sap volumes have been in the range of 20 to 60 pl. For obtained sap volumes >20 pl division of the sample droplet into subsamples is possible. This allows repeated injections into the CE and thus high reliability of the obtained data and, using different CE systems, the possibility of determination of many different species in one vacuolar sample. This is demonstrated with the determination of inorganic cation and anion concentrations in the same vacuole of individual wheat epidermal cells using indirect UV detection. The applicability of CE for vacuolar analysis is illustrated with the identification of intercellular solute patterns between different wheat epidermal cell types.