Resistance to the gravitational force is one of two major graviresponses in plants. However, only limited information has been obtained for its mechanism. The Resist Wall experiment aims to examine the role of the cortical microtubule-plasma membrane-cell wall continuum in gravity resistance, thereby clarifying its mechanism. For this purpose, we will cultivate Arabidopsis mutants defective in organization of cortical microtubules (tua6) or synthesis of membrane sterols (hmg1) as well as the wild type Columbia under microgravity and 1G conditions in the European Modular Cultivation System on the International Space Station up to reproductive stage, and compare phenotypes on growth and development using video images. These mutants are unable to form the normal cell wall and show disordered growth pattern on Earth. However, it is expected that the defects of such mutants are rescued and they can grow and develop more or less normally under microgravity in space, where formation of the tough cell wall is not required. We will also analyze changes in expression of genes involved in formation of the continuum and properties of related cellular components under microgravity conditions. The results of the Resist Wall experiment will clarify the molecular mechanism of gravity resistance and benefit efficient plant production not only in space but on Earth.
2007 by Japanese Society for Biological Sciences in Space