Sievers A, Hejnowicz Z
Botanisches Institut, Universität Bonn, Venusbergweg, Germany.
ASGSB Bull. 1992 Oct;5(2):69-75.
The effect of clinostatting and microgravity on plant cells and organs is considered on the basis of distinguishing two types of gravistimulation: static and dynamic. The former is switched off both by clinostatting and microgravity, the latter is switched off by microgravity but occurs inevitably during clinostatting and may be perceived by cells if the rotation is not fast enough. Effects of clinostatting and microgravity on different examples of static gravistimulation (tonic effects, formation of compression wood, growth of "grass nodes," compensation of epinasty, stabilization of cellular polarity) are considered. The mechanism of the dynamic stimulation is presented; it is related to the displacement of the gravity sensing masses in the cell containing them, and involves disturbance of cytoskeletal tension. The low threshold for gravity perception and short minimal time of dynamic stimulation are emphasized. Only a relatively fast rotating clinostat, on which the radial distance of the cells from the rotational axis is small enough to keep the centrifugal force low, can effectively compensate gravity. However, one must take into account the extreme sensitivity of plants to mechanical stresses that may appear during clinostatting at different levels of plant organization.
基于区分两种类型的重力刺激（静态和动态），研究了回转器处理和微重力对植物细胞和器官的影响。前者通过回转器处理和微重力均被消除，后者通过微重力被消除，但在回转器处理过程中不可避免地会出现，并且如果旋转速度不够快，细胞可能会感知到。考虑了回转器处理和微重力对静态重力刺激的不同实例（紧张效应、受压木的形成、“草节”的生长、偏上性的补偿、细胞极性的稳定）的影响。提出了动态刺激的机制；它与包含重力感应物质的细胞中重力感应物质的位移有关，并涉及细胞骨架张力的干扰。强调了重力感知的低阈值和动态刺激的最短时间。只有相对快速旋转的回转器，其上细胞到旋转轴的径向距离足够小以保持离心力较低，才能有效地补偿重力。然而，必须考虑到植物对回转器处理过程中在不同植物组织水平可能出现的机械应力的极端敏感性。
