ELECTRON-MICROSCOPY AND ELECTROPHYSIOLOGY OF LOCAL CELL-WALL FORMATION IN CHARA-CORALLINA

The formation of fibrillar and amorphous local wall appositions induce d by wounding and treatment with chlortetracycline (CTC) was studied i n internodal cells of Chara corallina. Wounding causes a transient dep olarisation of the membrane and a transient increase in membrane condu ctance. The formation of a fibrillar, cellulosic wound wall starts aft er the cell wall lesion has been plugged by vacuolar crystals and cyto plasmic inclusions. At that time both membrane potential and membrane conductance have recovered their normal values. CTC induces a persiste nt electrophysiological response and formation of the amorphous, callo se-containing wall appositions takes place at low (more positive) memb rane potential and low membrane resistance, suggesting an increased pa ssive membrane permeability. The electrophysiological changes increase with the Ca2+ concentration of the CTC solution. The relevance of the membrane potential for the formation of local wall appositions is dis cussed.