title: Measuring the distribution of cellulose microfibril angles in primary cell walls by small angle X-ray scattering.
abstract: BACKGROUND
  X-ray scattering is a well-established method for measuring cellulose microfibril angles in secondary cell walls. However, little data is available on the much thinner primary cell walls. Here, we show that microfibril orientation distributions can be determined by small angle X-ray scattering (SAXS) even in primary cell walls. The technique offers a number of advantages: samples can be analyzed in the native hydrated state without any preparation which minimizes the risk of artifacts and allows for fast data acquisition. The method provides data averaged over a specimen region, determined by the size of the used X-ray beam and, thus, yields the microfibril orientation distribution within this region.
  
  
  RESULTS
  Cellulose microfibril orientation distributions were obtained for single cells of the alga Chara corallina, as well as for the multicellular hypocotyl of Arabidopsis thaliana. In both, Chara and Arabidopsis, distributions with a broad scattering around mean microfibril angles of approximately 0° and 90° towards the longitudinal axis of the cells were found.
  
  
  CONCLUSIONS
  With SAXS, the structure of primary cell walls can be analysed in their native state and new insights into the cellulose microfibril orientation of primary cell walls can be gained. The data shows that SAXS can serve as a valuable tool for the analysis of cellulose microfibril orientation in primary cell walls and, in consequence, add to the understanding of its mechanical behaviour and the intriguing mechanisms behind cell growth.
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany.
authors.forename: Friederike
authors.initials: F
authors.lastname: Saxe
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Eder
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany.
authors.forename: Gunthard
authors.initials: G
authors.lastname: Benecke
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Aichmayer
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Fratzl
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany ; Swiss Federal Institute of Technology Zurich, Institute for Building Materials, 8093 Zurich, Switzerland ; Swiss Federal Laboratories for Materials Science and Technology, Applied Wood Materials Laboratory, 8600 Duebendorf, Switzerland.
authors.forename: Ingo
authors.initials: I
authors.lastname: Burgert
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, 14476, Germany ; Swiss Federal Institute of Technology Zurich, Institute for Building Materials, 8093 Zurich, Switzerland ; Swiss Federal Laboratories for Materials Science and Technology, Applied Wood Materials Laboratory, 8600 Duebendorf, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Rüggeberg
keywords: Arabidopsis thaliana; Cellulose microfibril orientation; Chara corallina; Primary cell wall; X-ray scattering