They are hypothesized to play important roles in cell-cell interaction, including the possible exchange of informational macromolecules involved in development. Very little is known about the components that make up plasmodesmata, including the genes that encode the components, how the plasmodesmata are assembled at particular cell junctions, or how communication through them may be regulated. The researchers hope to exploit the new GFP tag as an entry point to pursue these questions. Confocal imaging of GFP is proving to be a robust method for visualizing cell behavior, including behavior related to morphogenesis. The group is employing their collection of GFP markers to study the mechanism of cytokinesis in Arabidopsis shoot cells.
Plant cells divide very differently from animal cells.
In plants, a new cell partition is initiated as an internally assembled structure, a phragmoplast, before it is fused to the parental cell membrane. It is during phragmoplast development that some plasmodesmal channels are initiated. Confocal imaging of GFP is opening a new window on cell division by giving researchers the ability to visualize three-dimensional aspects of cytokinesis as it occurs in living cells. This technique provides access to cells that were previously difficult to observe, such as those in the shoot epidermis and cortex, permitting the researchers to address questions about how these cells perform cytokinesis in their native multicellular context. The variety of GFP markers that the group has isolated is also allowing them to extend questions about cytokinesis to the behavior of discreet organelles and cell compartments.