title: Chlorogenic acid facilitates root hair formation in lettuce seedlings.
abstract: Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. A low pH (pH 4) medium induced root hair formation in lettuce (Lactuca sativa L.) seedlings, and the decapitation of shoots inhibited root hair formation. The addition of shoot extract to the medium restored root hair formation in the decapitated lettuce seedlings. These results suggest that factors essential to the formation of root hairs may be present in the shoot. We purified one factor from the shoot that facilitates root hair formation. This factor was identified as chlorogenic acid (CGA), a common polyphenol in higher plants. The presence of exogenous CGA in the medium induced root hair formation in decapitated lettuce seedlings at pH 4.0 and in intact lettuce seedlings at pH 6.0. The optimum concentration of CGA for root hair formation was identified as 10(-5) M. Decapitation of the shoots reduced the CGA content in the roots to approximately one-third that in intact plants. Application of the CGA biosynthesis inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP, 10(-6) M) to intact seedlings grown at pH 4.0 reduced both the CGA content of the roots and the total amount of root hairs. The addition of exogenous CGA restored root hair formation in intact seedlings treated with AOPP. These results suggest that CGA is essential for root hair formation in lettuce seedlings.
authors.affiliation: Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda, Chiba 278-8510, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Narukawa
authors.forename: Kaori
authors.initials: K
authors.lastname: Kanbara
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tominaga
authors.forename: Yurika
authors.initials: Y
authors.lastname: Aitani
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Fukuda
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kodama
authors.forename: Noriko
authors.initials: N
authors.lastname: Murayama
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Nara
authors.forename: Takashi
authors.initials: T
authors.lastname: Arai
authors.forename: Masae
authors.initials: M
authors.lastname: Konno
authors.forename: Shinji
authors.initials: S
authors.lastname: Kamisuki
authors.forename: Fumio
authors.initials: F
authors.lastname: Sugawara
authors.forename: Masako
authors.initials: M
authors.lastname: Iwai
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D002726:Chlorogenic Acid / Q000302:isolation & purification / Q000378:metabolism*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D018545:Lactuca / Q000254:growth & development*; D010649:Phenylalanine / Q000031:analogs & derivatives; D018517:Plant Roots / Q000254:growth & development* / Q000648:ultrastructure; D036226:Seedlings / Q000254:growth & development*
chemical_list: D003470:Culture Media; D002726:Chlorogenic Acid; C019145:alpha-aminooxy-beta-phenylpropionic acid; D010649:Phenylalanine