9 - The Mechanism of Movement in Plants

Abstract

Plants possess the capacity for movement in one or another form, including protoplasmic movement, the coordinate movements of chromosomes occurring during mitosis, movement of sperms, and the movement of leaves. Although there are no complex differentiated systems as found in muscles of animals, there is not much information on the mechanism of movement in higher plants. This chapter discusses the problem of the motor reaction in plants. This chapter presents an investigation of plants whose leaves are capable of a motor reaction, viz. plants capable of nictinastic movements, seismonastic movements, and autonomous movements. The chapter presents a study in which high ATP-ase activity was found in leaves of plants capable of executing any of these types of movement, negligible activity in the leaves of most plants not possessing the faculty of movement, including even instances where the plants were closely related to the motile ones. The ATP-ase protein is most active at the pH region 5–6, in which respect it differs from muscle ATP-ase. The addition of Ca++ and Mg++ does not materially affect the enzymatic activity, although the addition of the sodium salt of EDTA, which binds Ca++ and Mg++, greatly decreases ATP-ase activity.