Solute distribution in Suaeda maritima.

The distribution of sodium, potassium and glycinebetaine in shoot tissues of salt-treated Suaeda maritima was examined by semi-micro techniques after extraction into toluene-water. Much higher K/Na ratios were observed in the apical regions and in axillary buds than in more mature, fully vacuolated tissues. The younger tissues also contained very high levels of glycinebetaine. Electron-probe X-ray microanalysis of bulkfrozen and fractured preparations showed higher K/Na ratios and higher levels of sulphur and phosphorus in the cytoplasm of leaf primordial cells than in vacuoles of either young or old leaves, although the total counts were higher in the vacuolar samples. The results are discussed in relation to current models of subcellular solute compartmentation and salt tolerance in the Chenopodiaceae.