Callose formation in injured cells of the vegetative and generative thallus of Chara vulgaris L. Absence of callose in the process of cytodifferentiation

Abstract

In an alga <em>Chara vulgaris</em> L. the processes of differentiation of vegetative system cells of the thallus, and initiation and development of generative organs are not associated with callose formation. It was demonstrated that damage to any of the somatic cells and also generative and nongenerative cells of the antheridium and oogonium are capable of callose formation independently of their developmental stage. The localisation and thickness of these layers depend on the way the cells are injured and on their size. The protective role of callose in such cells may consist, beside strengthening the damaged walls, in protection of the symplast by formation of callose deposits on the walls with plasmodesmata; it may also consist in increasing the water potential of the cells. Experiments in which callose deposition was provoked by pressing of the cells or damage leading to a sudden increase of the water potential of the extracellular environment suggest that a sudden increase of tension in the cells may be a factor triggering the "callose effect".