title: Joining forces: the interface of gravitropism and plastid protein import.
abstract: In flowering plants, gravity perception appears to involve the sedimentation of starch-filled plastids, called amyloplasts, within specialized cells (the statocytes) of shoots (endodermal cells) and roots (columella cells). Unfortunately, how the physical information derived from amyloplast sedimentation is converted into a biochemical signal that promotes organ gravitropic curvature remains largely unknown. Recent results suggest an involvement of the Translocon of the Outer Envelope of (Chloro)plastids (TOC) in early phases of gravity signal transduction within the statocytes. This review summarizes our current knowledge of the molecular mechanisms that govern gravity signal transduction in flowering plants and summarizes models that attempt to explain the contribution of TOC proteins in this important behavioral plant growth response to its mechanical environment.
authors.affiliation: Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: John
authors.initials: J
authors.lastname: Stanga
authors.forename: Katherine
authors.initials: K
authors.lastname: Baldwin
authors.forename: Patrick H
authors.initials: PH
authors.lastname: Masson
mesh_terms: D017343:Genes, Plant; D018522:Gravitropism / Q000235:genetics / Q000502:physiology*; D018466:Gravity Sensing / Q000235:genetics / Q000502:physiology*; D008954:Models, Biological; D018521:Plant Physiological Phenomena / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000502:physiology; D018520:Plant Shoots / Q000502:physiology; D018087:Plastids / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction