DEVELOPMENT OF THE ENVIRONMENTAL SENSOR FUNCTION IN A PLANT LEAF

A plant leaf responded markedly to CO2 stress by changing its cellular potential. Moreover its response pattern were modified by coexistence of small amount of odor compounds, which suggested the presence of excellent sensing function of a plant leaf for odor compounds. In this study, I have analyzed the CO2 stress response electrochemically with multi-microelectrode system. At first, I have clarified that epidermal cells of Tradescantia virginiana L. within a radius of about 2 mm are electrically short-circuited. Electrochemically, however, they have been found isolated from each other. Based on the electron microscopic analysis and the dye diffusion experiment, I constructed a leaf structure model. Intracellular responses corresponded to the vacuolar potential change. Since the potential change could not be elucidated without taking the electrogenic potential into account, I proved the existence of H+-ATPase in the vacuolar membrane of T. virginiana which can generate the electrogenic potential. As the result, the mechanism of CO2 stress response was explained by the diffusion potential K+ and H+, and the electrogenic potential of H+.