In this proposal the PI will address physiolgical and structural questions concerning the contribution of calcium (Ca) to three specific plant systems: 1) cytokinin-induced bud formation in Funaria, 2) phytochrome-stimulated spore germination in Onoclea, and 3) germination and pollen tube growth in Tradescantia and Nicotiana. In the physiolgical studies he will determine if the intracellular free Ca changes in response to a stimulus. The kinetics of Ca changes will be examined micro- spectrophotometrically in target cells of Funaria that have been microinjected with the absorbant Ca-indicator dye arsenazo-III. Particular attention will also be given to the role of the phosphatidyl inositol (PI) cycle in mediating development. Pharmacological agents that enhance or inhibit portions of the PI cycle will be tested for their effect on development. Structural studies will focus on cytoskeletal and membrane components. The ability of fluxes in Ca to modify these components will be analyzed at the light microscope level using fluorescent stains and antibodies, and at the electron microscope level using material that has been prepared by a rapid freeze fixation method, in which cytoplasmic structure is preserved with exceptional fidelity. Calcium ions act as intracellular messengers in many organisms. They are thought to couple the stimulus to the response and thus to mediate or trigger many important developmental events. The role of calcium ions as intracellular messengers has not been as well studied in plants. These studies will contribute to an understanding of the role of Ca in stimulus/response coupling in plants.
