Recovery of Geotropism after Removal of the Root Cap

Removal of the cap from the primary roots of Zea mays and Triticum aestivum renders the roots unresponsive to gravity. In both species a geotropic response is recovered before a new cap has started to regenerate. Immediately after decapping amyloplasts start to develop in cells of the root apex and it is proposed that as the development of amyloplasts continues so they become functional as gravity sensors. It is also suggested that the amyloplasts may be the source of an inhibitor that has been postulated to be the intermediary between the perception of gravity and the geotropic response.