title: Plastids:  dynamic components of plant cell development.
abstract: The gravitropic bending of maize roots, as a response to reorientation of the root within a gravitational field, was examined for sensitivity to exogenous applications of the cytoskeletal inhibitor, cytochalasin D. Agar blocks were impregnated with this inhibitor, and were applied either to the root cap or to the zone of root cell elongation.  Root growth was normal with either treatment, if the roots were not repositioned with respect to the gravitational vector.  When untreated roots were placed in a horizontal position with respect to gravity, a 40 degree bending response was observed within one hour.  This bending also occurred when cytochalasin D was applied at high concentrations to the zone of root cell elongation.  However, when cytochalasin D above 40 micrograms/ml was applied to the root cap, roots lost the ability of directional reorientation within the gravitational field, causing a random bending.
authors.affiliation: Division of Biology, Kansas State University, Manhattan 66502, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Guikema
authors.forename: G L
authors.initials: GL
authors.lastname: Gallegos
mesh_terms: D015638:Cytochalasin D / Q000494:pharmacology*; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology*; D018522:Gravitropism / Q000187:drug effects* / Q000502:physiology*; D018518:Plant Root Cap / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018087:Plastids / Q000187:drug effects / Q000502:physiology*; D003313:Zea mays / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D015638:Cytochalasin D