Plant Gravitropism

Kouichi Soga, Sachiko Yano, Shouhei Matsumoto, Takayuki Hoson

Hypergravity generated by centrifugal acceleration is the only practical method to modify the magnitude of gravitational acceleration for a sufficient duration on Earth and has been used to analyze the nature and mechanism of graviresponse, particularly gravity resistance, in plants. Plant organs are generally resistant to gravitational acceleration. Hypergravity produced from centrifugation speeds in the range of 10-300 × g, which is easily produced by a benchtop centrifuge, is often used during plant experiments. After centrifugation, 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 sequentially used for determining the mechanical properties of the cell wall, for RNA extraction (which is necessary for gene expression analysis), for estimating the enzyme activity of the cell wall proteins, and for determining the levels as well as the compositions of cell wall polysaccharides. The plant material can also be used directly for microscopic observation of cellular components such as cortical microtubules.