Laboratory for Cognitive Systems and Cybernetics Research, Center for Soft Computing Research, Indian Statistical Institute, Kolkata, 700 108, India.
Agriculture and Ecological Research Unit, Indian Statistical Institute, Kolkata, India.
J Plant Res. 2023 Mar;136(2):265-276. doi: 10.1007/s10265-023-01434-y. Epub 2023 Jan 21.
Plants' ability to sense and respond to gravity is a unique and fundamental process. When a plant organ is tilted, it adjusts its growth orientation relative to gravity direction, which is achieved by a curvature of the organ. In higher, multicellular plants, it is thought that the relative directional change of gravity is detected by starch-filled organelles that occur inside specialized cells called statocytes, and this is followed by signal conversion from physical information to physiological information within the statocytes. The classic starch statolith hypothesis, i.e., the starch accumulating amyloplasts movement along the gravity vector within gravity-sensing cells (statocytes) is the probable trigger of subsequent intracellular signaling, is widely accepted. Acharya Jagadish Chandra Bose through his pioneering research had investigated whether the fundamental reaction of geocurvature is contractile or expansive and whether the geo-sensing cells are diffusedly distributed in the organ or are present in the form of a definite layer. In this backdrop, a microscopy based experimental study was undertaken to understand the distribution pattern of the gravisensing layer, along the length (node-node) of the model plant Alternanthera philoxeroides and to study the microrheological property of the mobile starch-filled statocytes following inclination-induced graviception in the stem of the model plant. The study indicated a prominent difference in the pattern of distribution of the gravisensing layer along the length of the model plant. The study also indicated that upon changing the orientation of the plant from vertical position to horizontal position there was a characteristic change in orientation of the mobile starch granules within the statocytes. In the present study for the analysis of the microscopic images of the stem tissue cross sections, a specialized and modified microscopic illumination setup was developed in the laboratory in order to enhance the resolution and contrast of the starch granules.
植物感知和响应重力的能力是一个独特而基本的过程。当植物器官倾斜时，它会相对于重力方向调整其生长方向，这是通过器官的弯曲来实现的。在更高等的多细胞植物中，人们认为相对重力方向的变化是由充满淀粉的细胞器检测到的，这些细胞器存在于专门的细胞中，称为平衡石细胞，随后在平衡石细胞内将物理信息转换为生理信息。经典的淀粉平衡石假说，即淀粉积累的造粉体沿重力感受细胞（平衡石细胞）中的重力向量运动，是随后细胞内信号传导的可能触发因素，这一假说被广泛接受。阿查里亚·贾格迪什·钱德拉·博斯通过开创性的研究，调查了地曲率的基本反应是收缩还是扩张，以及地感细胞是否在器官中扩散分布，还是以确定的层形式存在。在此背景下，进行了一项基于显微镜的实验研究，以了解模型植物Alternanthera philoxeroides 中沿长度（节间）的重力感应层的分布模式，并研究模型植物茎中因倾斜引起的重感而导致的可移动充满淀粉的平衡石细胞的微流变特性。该研究表明，重力感应层在模型植物长度上的分布模式存在明显差异。该研究还表明，当植物的方向从垂直位置变为水平位置时，平衡石细胞内的可移动淀粉颗粒的方向会发生特征性变化。在本研究中，为了分析茎组织切片的显微镜图像，在实验室中开发了一种专门的、改进的显微镜照明装置，以提高淀粉颗粒的分辨率和对比度。
