Perbal G, Driss-Ecole D
Laboratoire CEMV, Université Pierre et Marie Curie, Paris, France.
Adv Space Res. 1994;14(8):11-9. doi: 10.1016/0273-1177(94)90381-6.
The amyloplasts of root statocytes are considered to be the perceptors of gravity. However, their displacement and the starch they contain are not required for gravisensing. The mechanism of the transduction of gravistimulus remains therefore controversial. It is well known that the amplitude of the stimulus is dependent upon the intensity of the acceleration and the inclination of the root with respect to gravity. This strongly supports the hypothesis that the stimulus results in a mechanical effect (pressure or tension) on a cellular structure. Three cellular components are proposed as possible candidates for the role of transducer: the actin filaments, the endoplasmic reticulum and the plasma membrane with its ion channels. Recent results obtained in the frame of the IML 1 Mission of Spacelab show that the endoplasmic reticulum should rather be responsible for the termination of the stimulus. The contacts of amyloplasts with the distal ER could therefore be involved in the regulation of root growth.
根平衡细胞的造粉体被认为是重力感受器。然而，造粉体的位移及其所含的淀粉对于重力感知并非必需。因此，重力刺激的转导机制仍存在争议。众所周知，刺激的幅度取决于加速度的强度以及根相对于重力的倾斜度。这有力地支持了这样一种假说，即刺激会对细胞结构产生机械效应（压力或张力）。有三种细胞成分被认为可能是转导器的候选者：肌动蛋白丝、内质网以及带有离子通道的质膜。在空间实验室IML 1任务框架内获得的最新结果表明，内质网更应该是刺激终止的原因。因此，造粉体与内质网远端的接触可能参与根生长的调节。
