PINOCYTOSIS AND ITS POSSIBLE ROLE IN ION-TRANSPORT IN THE SALT-ACCUMULATING ORGANS OF HALOPHYTES

The ultrastructural organization of cells was investigated in the shoo ts of salt-accumulating halophytes Seidlitzia rosmarinus (Ehrh.) Bunge , Salicornia europaea L., Climacoptera lanata (Pall.) Botsh., and Suae da arcuata Bunge. The plants were grown in soil or sand culture at an NaCl content of 400 mmol/dm3. Pinocytic invaginations were often found in the shoot cells, as a rule, bound by a double membrane (plasmalemm a and tonoplast), and protruded deeply into the vacuole. In addition, we observed ''floating'' multivesicular bodies in the vacuoles, which apparently originated from pinocytic invaginations. Both the invaginat ions and the multivesicular bodies were filled with vesicles, tubules, and myelin-like formations. By the moment of fixation for electron mi croscopy, the shoots had accumulated sodium in amounts exceeding its c ontent in the surrounding medium by 2 - 2.5 times. Using an electron-c ytochemical method, it was shown that chloride ions were localized mos tly in the vacuoles and the cell wall. We suggest that pinocytosis is instrumental in ion transport from the apoplast and in ion accumulatio n in the vacuoles of the shoots cells in salt accumulating halophytes.