Research in my laboratory employs molecular and electrophysiological techniques to elucidate the second messenger pathways by which signals such as light and hormones are transduced into cellular responses. The major cell type studied in my laboratory is the guard cell. Pairs of guard cells in the leaf epidermis regulate the apertures of stomatal pores, through which both transpirational water loss and carbon dioxide uptake occur. Regulation of the stomatal pores is vital so that the plant neither dries out nor is deprived of the carbon dioxide necessary for photosynthesis and growth. Stomatal apertures are controlled by osmotic swelling and shrinking of the guard cells, driven in turn by uptake or loss of potassium and other ions through ion channels located in the guard cell membrane.
Ion channels are membrane-spanning proteinaceous pores.
We apply the electrophysiological technique of patch clamping to guard cells in order to monitor in real time changes in ionic current that result from the opening and closing of individual ion channels. We also use patch clamping in the whole cell mode to simultaneously manipulate the biochemical milieu of the cytosol and observe effects on ion channel kinetics. We have also gained evidence that G-proteins, which regulate ion channels in animal systems, do so in plant systems as well. In order to identify the particular G-proteins involved in plant ion channel regulation, we are pursuing molecular genetic approaches. Plant Physiol .