2010 年 24 巻 3_4 号 p. 129-134
Gravity resistance is a response that enables the plants to develop against the gravitational force. We have analyzed the nature and mechanisms of gravity resistance using both hypergravity conditions produced by centrifugation and microgravity conditions in space. As the final step of gravity resistance, plants develop a short and thick body and increase the cell wall rigidity in response to the magnitude of the gravitational force. Prompt reorientation of cortical microtubules is involved in the modification of body shape. The regulation of the cell wall rigidity is brought about by modification of the metabolisms of anti-gravitational cell wall polysaccharides and changes in the pH of cell wall fluid. Plants may perceive the gravitational force independently of the direction of stimuli by mechanoreceptors on the plasma membrane in gravity resistance. The development of gravity resistance may serve an important function in the transition of plant ancestors from an aquatic environment to a terrestrial environment.