Mapping of cell wall aromatic moieties and their effect on hygroscopic movement in the awns of stork’s bill

Yael Abraham, Yonghui Dong, Asaph Aharoni, Rivka Elbaum

Research output: Contribution to journalArticlepeer-review


Abstract: The awn in stork’s bill (Erodium gruinum) seed dispersal units coils as it dries. This hygroscopic movement promotes the dissemination and sowing of the seeds. Here we aimed to understand the movement rate, by correlating water dynamics within the awn to the spatial variation in the chemical composition of the awn’s cell walls. We followed the hygroscopic movement visually and measured the kinetics of water adsorption–desorption in segments along the awn. We integrated data from white light, fluorescence, and Raman microscopy, and Matrix Assisted Laser Desorption Ionization imaging to characterize the micro chemical makeup of the awn. We hydrolyzed awns and followed the change in the cell walls’ composition and the effect on the movement. We found that the coil’s top segment is more sensitive to humidity changes than the coil’s base. At the top part of the coil, we found high concentration of modified lignin. In comparison, the base part of the awn contained lower concentration of mostly unmodified lignin. Ferulic acid concentration increased along the awn, apparently cross-linking hemicellulose and strengthening cell-to-cell adhesion. We propose that the high concentration of modified lignin at the coil’s top increased the hydrophobicity of the cell walls, allowed faster water molecules dynamics; thus inducing fast reaction to ambient humidity. Strong cell-to-cell adhesion in this region created a durable tissue required for the awn’s repeated movement that is induced by the diurnal humidity cycles.

Original languageAmerican English
Pages (from-to)3827-3841
Number of pages15
Issue number7
Early online date22 May 2018
StatePublished - 1 Jul 2018


  • Cell wall
  • Erodium gruinum
  • Ferulic acid
  • Fluorescence microscopy
  • Hygroscopic movement
  • Lignin
  • Raman microspectroscopy

All Science Journal Classification (ASJC) codes

  • Polymers and Plastics


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