Abstract: All life on the earth has usually evolved within the force of earth’s gravitational field and has acquired the ability to gravistumili to regulate their growth and development. Although the directional growth of plants in response to gravity has continued been studies for over a century, but the cellular and molecular mechanisms underlying the gravitropic response of plants still remain to be understood. The cytoskeleton is considered as an important organelle in mediating early sensing and signal transduction events in plant gravitropism. There are a lot of evidences indicating that the role of actin cytoskeleton in regulating auxin polar transport, which induces a lateral gradient of auxin and results in plant organ curvature. The reorientation of microtubules in plant cells during gravitropic response was also reported, but the role of this reorganization of microtubules in controlling the differential gravitropic growth has not been clear. The advances in cellular, molecular and biochemical techniques have provided several possibilities for further research into this fascinating area. The new findings in characterization of cytoskeleton binding proteins have provided us a lot of useful information on various kinds of candidate regulators that could be targets of the gravity signal transduction chain. In this paper, the functions of cytoskeleton in gravitropism are discussed and the update progress in plant space biology is also introduced.

Key words: actin, cell elongation, cytoskeleton, gravitropsim, microtubules, signal transduction.