Understanding the Mechanisms of Gravity Resistance in Plants.

To understand gravity resistance in plants, it is necessary to analyze the changes induced when the magnitude of gravity in a growth environment is modified. Microgravity in space provides appropriate conditions for analyzing gravity resistance mechanisms. Experiments carried out in space involve a large number of constraints and are quite different from ground-based experiments. Here, we describe basic procedures for space-based experiments to study gravity resistance in plants. An appropriate cultivation chamber must be selected according to the growing period of the plants and the purpose of the experiment. After cultivation, the plant material is fixed with suitable fixatives in appropriate sample storage containers such as the Chemical Fixation Bag. The material is then analyzed with a variety of methods, depending on the purpose of the experiment. Plant material fixed with the RNAlater solution can be used sequentially to determine the mechanical properties of the cell wall, RNA extraction (which is necessary for gene-expression analysis), estimate the enzyme activity of cell wall proteins, and measure the levels and compositions of cell wall polysaccharides. The plant material can also be used directly for microscopic observation of cellular components such as cortical microtubules.