Transduction of the gravity stimulus in the root statocyte

• Published in: Advances in space research Vol. 14; no. 8; pp. 11 - 19
• Main Authors: Perbal, G., Driss-Ecole, D.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.1994
• Subjects: Actin Cytoskeleton - chemistry; Actin Cytoskeleton - physiology; Actins - analysis; Cell Membrane - physiology; Cytoskeleton - chemistry; Cytoskeleton - physiology; Endoplasmic Reticulum - chemistry; Endoplasmic Reticulum - physiology; Fabaceae - cytology; Fabaceae - growth & development; Fabaceae - physiology; Gravitropism - physiology; Gravity Sensing - physiology; Plant Root Cap - cytology; Plant Root Cap - growth & development; Plant Root Cap - physiology; Plant Roots - cytology; Plant Roots - growth & development; Plant Roots - physiology; Plants, Medicinal; Plastids - physiology; Signal Transduction - physiology; Space Flight; Space life sciences; Weightlessness; Zea mays - cytology; Zea mays - growth & development; Zea mays - physiology; NASA Experiment Number ROOTS
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/0273-1177(94)90381-6

The amyloplasts of root statocytes are considered to be the perceptors of gravity. However, their displacement and the starch they contain are not required for gravisensing. The mechanism of the transduction of gravistimulus remains therefore controversial. It is well known that the amplitude of the stimulus is dependent upon the intensility of the acceleration and the inclination of the root with respect to gravity. This strongly supports the hypothesis that the stimulus results in a mechanical effect (pressure or tension) on a cellular strcuture. Three cellular components are proposed as possible candidates for the role of transducer : the actin filaments, the endoplasmic reticulum and the plasma membrane with its ion channels. Recent results obtained in the frame of the IML 1 Mission of Spacelab show that the endoplasmic reticulum should rather be responsible for the termination of the stimulus. The contacts of amyloplasts with the distal ER could therefore be involved in the regulation of root growth.