Abstract

The rapid turgor movements of Mimosa pudica and some carnivorous plants have long stimulated the interest of botanists. In addition, it is becoming evident that slower responses of plants to mechanical stimuli, such as coiling of tendrils and thigmomorphogenesis, are common phenomena. Electrophysiological studies on mechano-perception have been carried out in M. pudica and carnivorous plants, and have established that the response to mechanical stimulation is composed of three steps: perception of the stimulus, transmission of the signal, and induction of movement in motor cells. The first step is due to the receptor potential, the second and third steps are mediated by the action potential. In this article, the mechanisms of responses to mechanical stimuli of these plants are considered. Since higher plants are composed of complex tissues, detailed analysis of electrical phenomena is rather difficult, and so the mechanism for generating the receptor potential had not yet been studied. Characean cells have proved to be more amenable to the study of the electrophysiology of plant membranes because of their large cell size and the ease by which single cells can be isolated. Recent progress in studies of the receptor potential in characean cells is also discussed.