title: Gravitropic response and circumnutation in pea (Pisum sativum) seedling roots.
abstract: Plant circumnutation is a helical movement of growing organs such as shoots and roots. Gravitropic response is hypothesized to act as an external oscillator in shoot circumnutation, although this is subject to debate. The relationship between circumnutational movement and gravitropic response in roots remains unknown. In this study, we analyzed circumnutation of agravitropic roots using the ageotropum pea (Pisum sativum) mutant, and compared it with that of wild-type (cv. Alaska) pea roots. We further examined the relationship of gravitropic response to circumnutation of Alaska seedling roots by removing the gravisensing tissue (the root cap) and by treating the roots with auxin transport inhibitors. Alaska roots displayed circumnutational movements with a period of approximately 150 min, whereas ageotropum roots did not exhibit distinct circumnutational movement. Removal of the root cap in Alaska roots reduced gravitropic response and circumnutational movements. Treatment of Alaska roots with auxin transport inhibitors, 2,3,5-triiodobenzoic acid (TIBA) and N-(1-naphthyl)phthalamic acid (NPA), dramatically reduced gravitropic response and circumnutational movements. These results suggest that a gravity-regulated auxin transport is involved in circumnutation of pea seedling roots.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
authors.forename: Hye-jeong
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
authors.forename: Akie
authors.initials: A
authors.lastname: Kobayashi
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Department of Biology, Faculty of Science, Yamagata University, Yamagata, 990-8560, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miyazawa
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D001692:Biological Transport; D018522:Gravitropism / Q000187:drug effects / Q000502:physiology*; D007210:Indoleacetic Acids / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018532:Pisum sativum / Q000187:drug effects / Q000502:physiology*; D010797:Phthalimides / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology*; D036226:Seedlings / Q000187:drug effects / Q000502:physiology; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D007210:Indoleacetic Acids; D010797:Phthalimides; D010937:Plant Growth Regulators; D014283:Triiodobenzoic Acids; C002687:alpha-naphthylphthalamic acid; C052968:2,3,5-triiodobenzoic acid