ABSTRACT
Protoplasts can be viewed as injured cells which must embark on a program of repair before they are capable of sustained division, and thus cultured plant protoplasts are in a linear rather than a cyclical developmental sequence. Plant cells and plant protoplasts have in common the organelle which provides the signals by which progression through the cell cycle has traditionally been mapped, i.e., the nucleus. Plant cell and protoplast culture techniques are now sufficiently well advanced to allow sensible alternatives to the initial, crude attempts to genetically transform plant cells. Plant protoplasts are often the material of choice in genetic transformation studies, because the absence of the cell wall should presumably remove one barrier to DNA entry. The accumulation of cells in mitosis by the use of various inhibitors is sometimes erroneously referred to as cell cycle synchronization. In summary, cell cycle studies with plant protoplasts, although not presently in vogue among plant scientists, obviously have much to offer.
