title: Effects of locally targeted heavy-ion and laser microbeam on root hydrotropism in Arabidopsis thaliana.
abstract: Classical studies on root hydrotropism have hypothesized the importance of columella cells as well as the de novo gene expression, such as auxin-inducible gene, at the elongation zone in hydrotropism; however, there has been no confirmation that columella cells or auxin-mediated signaling in the elongation zone are necessary for hydrotropism. We examined the role of root cap and elongation zone cells in root hydrotropism using heavy-ion and laser microbeam. Heavy-ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporarily suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy-ion broad-beam irradiation suppressed de novo expression of INDOLE ACETIC ACID 5 gene, but not MIZU-KUSSEI1 gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that de novo gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi, Japan. miyazawa@ige.tohoku.ac.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miyazawa
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakashita
authors.forename: Tomoo
authors.initials: T
authors.lastname: Funayama
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Negishi
authors.forename: Akie
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kaneyasu
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ooba
authors.forename: Keita
authors.initials: K
authors.lastname: Morohashi
authors.forename: Takehiko
authors.initials: T
authors.lastname: Kakizaki
authors.forename: Seiichi
authors.initials: S
authors.lastname: Wada
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Fujii
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D020450:Heavy Ions; D007834:Lasers; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D010944:Plants; D011829:Radiation Dosage; D018523:Tropism / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D014867:Water / Q000494:pharmacology*
chemical_list: D014867:Water