The cell plate is a disc-like structure that is present only in dividing plant cells. Since cell plates are found only in plant cells, it is hoped that herbicides which directly and specifically block or interfere with cell plate development will be specific to plants and less hazardous to animals that may be exposed to such herbicides. Unfortunately, identifying such herbicides is hampered by a scarcity of tools and methods for rapidly and easily monitoring the effect of such herbicides on cell plate development.
Currently cell plate development is examined using phase contrast microscopy. However, some of the early stages of cell plate formation are difficult to examine using this tool. Cell plate development is also monitored by microscopic techniques in which the cells are first fixed and then incubated with aniline blue to stain the callose polysaccharide, which is a component of the cell wall. However, because callose is not deposited on the cell plate until the later stages of cell plate development, this technique also is not useful to monitor the early stages of cell plate formation and development.
The present invention provides new tools and methods for identifying herbicides and potential herbicides which affect cell plate formation and development. A new protein, phragmoplastin, has been discovered which is associated with cell plate membrane vesicles during cytokinesis. By visualizing the phragmoplastin, one is able to examine the development of the cell plate particularly in response to herbicides or potential herbicides. One method of visualizing phragmoplastin employs immunocytochemical techniques with anti-phragmoplastin antibodies. Another method of visualizing phragmoplastin employs cells which are transformed with a DNA molecule which encodes a chimeric phragmoplastin protein comprised of phragmoplastin and a luminescent tag or protein, fused to the phragmoplastin protein. The phragmoplastin in such cells is visualized by examining the cells under conditions which cause the marker to become visible such as by fluorescent microscopy.
Development of herbicides.
Herbicides that attack the cell plate will be less hazardous to humans and animals.