title: Biochemical and immunocytological characterizations of Arabidopsis pollen tube cell wall.
abstract: During plant sexual reproduction, pollen germination and tube growth require development under tight spatial and temporal control for the proper delivery of the sperm cells to the ovules. Pollen tubes are fast growing tip-polarized cells able to perceive multiple guiding signals emitted by the female organ. Adhesion of pollen tubes via cell wall molecules may be part of the battery of signals. In order to study these processes, we investigated the cell wall characteristics of in vitro-grown Arabidopsis (Arabidopsis thaliana) pollen tubes using a combination of immunocytochemical and biochemical techniques. Results showed a well-defined localization of cell wall epitopes. Low esterified homogalacturonan epitopes were found mostly in the pollen tube wall back from the tip. Xyloglucan and arabinan from rhamnogalacturonan I epitopes were detected along the entire tube within the two wall layers and the outer wall layer, respectively. In contrast, highly esterified homogalacturonan and arabinogalactan protein epitopes were found associated predominantly with the tip region. Chemical analysis of the pollen tube cell wall revealed an important content of arabinosyl residues (43%) originating mostly from (1-->5)-alpha-L-arabinan, the side chains of rhamnogalacturonan I. Finally, matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of endo-glucanase-sensitive xyloglucan showed mass spectra with two dominant oligosaccharides (XLXG/XXLG and XXFG), both being mono O-acetylated, and accounting for over 68% of the total ion signals. These findings demonstrate that the Arabidopsis pollen tube wall has its own characteristics compared with other cell types in the Arabidopsis sporophyte. These structural features are discussed in terms of pollen tube cell wall biosynthesis and growth dynamics.
authors.affiliation: Laboratoire de Glycobiologie et Matrice Extracellulaire Végétale, UPRES EA 4358, Institut Fédératif de Recherche Multidisciplinaire sur les Peptides 23, Université de Rouen, 76821 Mont Saint-Aignan cedex, France.
authors.forename: Flavien
authors.initials: F
authors.lastname: Dardelle
authors.forename: Arnaud
authors.initials: A
authors.lastname: Lehner
authors.forename: Yasmina
authors.initials: Y
authors.lastname: Ramdani
authors.forename: Muriel
authors.initials: M
authors.lastname: Bardor
authors.forename: Patrice
authors.initials: P
authors.lastname: Lerouge
authors.forename: Azeddine
authors.initials: A
authors.lastname: Driouich
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mollet
mesh_terms: D017360:Arabidopsis / Q000254:growth & development*; D002473:Cell Wall / Q000737:chemistry*; D008854:Microscopy, Electron; D009088:Mucoproteins / Q000737:chemistry; D010368:Pectins / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry; D053205:Pollen Tube / Q000254:growth & development* / Q000648:ultrastructure; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins; C042491:rhamnogalacturonan I; D010368:Pectins