Temperature‐dependent changes of electric potential differences on opposite sides of the tepals of Eranthis in relation to thermonastic responses
Electric potential differences (PDs) across the plasma membrane in cells of tepals of Eranthis hyemalis (L.) Salisb. were recorded under a regime in which the temperature was changed rapidly between two levels of approximately 8 and 19°C. The warming of an intact tepal resulted in a transient small increase in the magnitude of PD followed by a substantial long-lasting depolarization. Upon cooling the reverse response occurred: a small transient depolarization was followed by a substantial hyperpolarization. These responses were more pronounced in the epidermis on the abaxial side of the tepal than in that on the adaxial side, indicating an electrophysiological dorsiventrality of the tepals which may be related to thermonastic movements through differential proton secretion on the two sides.