title: The AMOR Arabinogalactan Sugar Chain Induces Pollen-Tube Competency to Respond to Ovular Guidance.
abstract: Precise directional control of pollen-tube growth by pistil tissue is critical for successful fertilization of flowering plants [1-3]. Ovular attractant peptides, which are secreted from two synergid cells on the side of the egg cell, have been identified [4-6]. Emerging evidence suggests that the ovular directional cue is not sufficient for successful guidance but that competency control by the pistil is critical for the response of pollen tubes to the attraction signal [1, 3, 7]. However, the female molecule for this competency induction has not been reported. Here we report that ovular methyl-glucuronosyl arabinogalactan (AMOR) induces competency of the pollen tube to respond to ovular attractant LURE peptides in Torenia fournieri. We developed a method for assaying the response capability of a pollen tube by micromanipulating an ovule. Using this method, we showed that pollen tubes growing through a cut style acquired a response capability in the medium by receiving a sufficient amount of a factor derived from mature ovules of Torenia. This factor, named AMOR, was identified as an arabinogalactan polysaccharide, the terminal 4-O-methyl-glucuronosyl residue of which was necessary for its activity. Moreover, a chemically synthesized disaccharide, the β isomer of methyl-glucuronosyl galactose (4-Me-GlcA-β-(1→6)-Gal), showed AMOR activity. No specific sugar-chain structure of plant extracellular matrix has been identified as a bioactive molecule involved in intercellular communication. We suggest that the AMOR sugar chain in the ovary renders the pollen tube competent to the chemotropic response prior to final guidance by LURE peptides.
authors.affiliation: JST ERATO, Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Akane G
authors.initials: AG
authors.lastname: Mizukami
authors.affiliation: Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Rie
authors.initials: R
authors.lastname: Inatsugi
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Jiao
authors.initials: J
authors.lastname: Jiao
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kotake
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kuwata
authors.affiliation: Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Ootani
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Satohiro
authors.initials: S
authors.lastname: Okuda
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Subramanian
authors.initials: S
authors.lastname: Sankaranarayanan
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Sato
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Maruyama
authors.affiliation: Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Iwai
authors.affiliation: Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
authors.forename: Estelle
authors.initials: E
authors.lastname: Garénaux
authors.affiliation: Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Sato
authors.affiliation: Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kitajima
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Tsumuraya
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Mori
authors.affiliation: Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Yamaguchi
authors.affiliation: Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Itami
authors.affiliation: Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
authors.forename: Narie
authors.initials: N
authors.lastname: Sasaki
authors.affiliation: JST ERATO, Higashiyama Live-Holonics Project, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan. Electronic address: higashi@bio.nagoya-u.ac.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Higashiyama
mesh_terms: D005685:Galactans / Q000378:metabolism*; D009088:Mucoproteins / Q000378:metabolism; D056771:Ovule / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D053205:Pollen Tube / Q000502:physiology*; D012098:Reproduction; D064028:Tracheophyta / Q000502:physiology*
chemical_list: D005685:Galactans; D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins; C005653:arabinogalactan
keywords: LURE attractant peptides; Torenia; arabinogalactan; competency control; ovule; pollen-tube guidance