Rapid movements in plants

Hiroaki Mano,Mitsuyasu Hasebe

doi:10.1007/s10265-020-01243-7

Abstract

Plant movements are generally slow, but some plant species have evolved the ability to move very rapidly at speeds comparable to those of animals. Whereas movement in animals relies on the contraction machinery of muscles, many plant movements use turgor pressure as the primary driving force together with secondarily generated elastic forces. The movement of stomata is the best-characterized model system for studying turgor-driven movement, and many gene products responsible for this movement, especially those related to ion transport, have been identified. Similar gene products were recently shown to function in the daily sleep movements of pulvini, the motor organs for macroscopic leaf movements. However, it is difficult to explain the mechanisms behind rapid multicellular movements as a simple extension of the mechanisms used for unicellular or slow movements. For example, water transport through plant tissues imposes a limit on the speed of plant movements, which becomes more severe as the size of the moving part increases. Rapidly moving traps in carnivorous plants overcome this limitation with the aid of the mechanical behaviors of their three-dimensional structures. In addition to a mechanism for rapid deformation, rapid multicellular movements also require a molecular system for rapid cell-cell communication, along with a mechanosensing system that initiates the response. Electrical activities similar to animal action potentials are found in many plant species, representing promising candidates for the rapid cell–cell signaling behind rapid movements, but the molecular entities of these electrical signals remain obscure. Here we review the current understanding of rapid plant movements with the aim of encouraging further biological studies into this fascinating, challenging topic.

Highlights

Both animals and plants exhibit a variety of macroscopic movements either autonomously or in response to external stimuli
We summarize the current knowledge on rapid plant movements, especially focusing on those actuated by biologically-active hydraulic processes, from a biomechanical and molecular biological perspective
A reactive oxygen species (ROS)-Ca2+ relay, whose signals travel at the speed of hundreds of micrometers per second (Choi et al 2014), is likely generated by the cooperative action of the vacuolar Ca2+ channel TPC1, the ROS-producing enzyme RBOHD, and as-yet-uncharacterized ROSactivated Ca2+ channels (Choi et al 2014; Evans et al 2016; Gilroy et al 2016) (Fig. 8d). These recent findings suggest that the generation of electrical signals associated with rapid plant movements is potentially mediated by a mechanism that differs from the classic action potential model

Summary

Introduction

Both animals and plants exhibit a variety of macroscopic movements either autonomously or in response to external stimuli. In concert with the molecular systems that control turgor pressure, the mechanical structures of the guard cell play pivotal roles in stomatal movement.

Results

Conclusion