ABSTRACT
Plant cells from which the cell wall has been removed are termed protoplasts. Protoplasts are somewhat unique in plant cell culture in that they exist as separate cells without cytoplasmic continuity among neighboring cells. Communication among protoplasts sharing the same culture environment is therefore limited to metabolites that can traverse the plasmalemma into the culture medium and influence the behavior of other cells. This limits the direct pathways of communication through cytoplasmic plasmodesmata generally present with intact plant tissues. However, in protoplast cultures, the barrier imposed by plant cell walls has also been eliminated. The plant cell wall, although critical to plant structure and function, is a major impediment in exploiting direct DNA transfer to individual cells and the production of somatic hybrids by cell fusion. Removal of the cell wall temporarily during protoplast culture can result in viable cells with properties otherwise unknown in plants.
