Title: A new scenario for gravity detection in plants: the position sensor hypothesis,
Abstract: The detection of gravity plays a fundamental role during the growth and
evolution of plants. Although progress has been made in our understanding of
the molecular, cellular and physical mechanisms involved in the gravity
detection, a coherent scenario consistent with all the observations is still
lacking. In this perspective paper we discuss recent experiments showing that
the response to inclination of shoots is independent of the gravity intensity,
meaning that the gravity sensor detects an inclination and not a force. This
result questions some of the commonly accepted hypotheses and leads to propose
a new "position sensor hypothesis". The implications of this new scenario are
discussed in the light of different observations available in the literature.