Gravisensitivity and automorphogenesis of lentil seedling roots grown on board the International Space Station
Gravisensitivity and automorphogenesis of lentil seedling roots grown on board the International Space Station
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DOI：
10.1111/j.1399-3054.2008.01121.x
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发表时间：
2008-09-01
影响因子：
6.4
通讯作者：
Perbal, Gerald
中科院分区：
文献类型：
--
作者：
Driss-Ecole, Dominique;Legue, Valerie;Perbal, Gerald
GRAVI-1 实验由发现号公司带上国际空间站（2006 年 12 月），并于 2007 年 1 月在欧洲模块化培养系统设施中进行。对于该实验的第一次运行，扁豆幼苗在微重力下水合并生长 15 小时，然后经受 0.29 x 10(-2) g 至 0.99 x 10(-2) g 的离心加速度 13 小时 40 分钟。在第二次运行期间，幼苗在微重力下生长 30 小时 30 分钟（该样品为对照）或 21 小时 30 分钟，然后承受 1.2 x 10(-2) g 至 2.0 x 10(-2) g 的离心加速度 9 小时。在这两种情况下，均通过延时摄影跟踪牙根方向和牙根曲率。实验期间，静态图像近乎实时地下载至地面挪威用户支持和运营中心。分析根尖位置和根曲率随时间的变化。研究表明，在微重力下，胚根强烈弯曲远离子叶（自形态发生），然后在水合后 17 至 30 小时缓慢伸直（自向性）。由于微重力下根部的自向伸直，在离心过程中 2 小时内，其尖端以接近最佳曲率角（120 度-135 度）的角度定向。此外，已经证明，刺激前在微重力下生长的扁豆根比在 1 g 下生长的根更敏感。在这些条件下，发现这些器官感知的阈值加速度在0和2.0 x 10(-3) g之间，并通过使用双曲线模型拟合实验数据并假设自向性对向地性响应没有或几乎没有影响，准确地估计为1.4 x 10(-5) g。平衡石的重力感应在如此低的加速度下应该是可能的，因为肌动球蛋白系统可以提供必要的功来克服重力感应的活化能。
The GRAVI-1 experiment was brought on board the International Space Station by Discovery (December 2006) and carried out in January 2007 in the European Modular Cultivation System facility. For the first run of this experiment, lentil seedlings were hydrated and grown in microgravity for 15 h and then subjected for 13 h 40 min to centrifugal accelerations ranging from 0.29 x 10(-2) g to 0.99 x 10(-2) g. During the second run, seedlings were grown either for 30 h 30 min in microgravity (this sample was the control) or for 21 h 30 min and then subjected to centrifugal accelerations ranging from 1.2 x 10(-2) g to 2.0 x 10(-2) g for 9 h. In both cases, root orientation and root curvature were followed by time-lapse photography. Still images were downlinked in near real time to ground Norwegian User Support and Operations Center during the experiment. The position of the root tip and the root curvature were analyzed as a function of time. It has been shown that in microgravity, the embryonic root curved strongly away from the cotyledons (automorphogenesis) and then straightened out slowly from 17 to 30 h following hydration (autotropism). Because of the autotropic straightening of roots in microgravity, their tip was oriented at an angle close to the optimal angle of curvature (120 degrees-135 degrees) for a period of 2 h during centrifugation. Moreover, it has been demonstrated that lentil roots grown in microgravity before stimulation were more sensitive than roots grown in 1 g. In these conditions, the threshold acceleration perceived by these organs was found to be between 0 and 2.0 x 10(-3) g and estimated punctually at 1.4 x 10(-5) g by using the hyperbolic model for fitting the experimental data and by assuming that autotropism had no or little impact on the gravitropic response. Gravisensing by statoliths should be possible at such a low level of acceleration because the actomyosin system could provide the necessary work to overcome the activation energy for gravisensing.