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Front. Plant Sci. | doi: 10.3389/fpls.2019.00684

Cytological approaches combined with chemical analysis reveals the layered nature of flax mucilage

 Fabien Miart1, Françoise Fournet1, Nelly Dubrulle2, Emmanuel Petit1, Hervé Demailly1,  Loic Dupont1, Luciane Zabijak1, Paulo Marcelo1,  Arezki Boudaoud2,  Christophe Pineau1,  Stéphanie Guénin1, Olivier Van Wuytswinkel1,  Francois Mesnard1 and  Karine PAGEAU1*
  • 1University of Picardie Jules Verne, France
  • 2École Normale Supérieure de Lyon, France

The external seed coat cell layer of certain species is specialized in the production and extrusion of a polysaccharide matrix called mucilage. Variations in the content of the released mucilage have been mainly associated with genetically regulated physiological modifications. Understanding the mucilage extrusion process in crop species is of importance to gain deeper insight into the complex cell wall biosynthesis and dynamics. In this study, we took advantage of the varying polysaccharide composition and the size of the flax mucilage secretory cells (MSCs) to study mucilage composition and extrusion in this species of agricultural interest. We demonstrate herein that flax MSCs are structured in four superimposed layers and that rhamnogalacturonans I (RG I) are firstly synthesized, in the upper face, preceding arabinoxylan and glucan synthesis in MSC lower layers. Our results also reveal that the flax mucilage release originates from inside MSC, between the upper and deeper layers, the latter collaborating to trigger polysaccharide expansion, radial cell wall breaking and mucilage extrusion in a peeling fashion. Here we provide evidence that the layer organization and polysaccharide composition of the MSCs regulate the mucilage release efficiency like a peeling mechanism. Finally, we propose that flax MSCs may represent an excellent model for further investigations of mucilage biosynthesis and its release.

Keywords: Cell Wall, Flax, mucilage, polysaccharides layers, Peeling mechanism, AX/RG I ratio.

Received: 21 Jun 2018; Accepted: 06 May 2019.

Edited by:

Christophe Dunand, Université Toulouse III Paul Sabatier, France

Reviewed by:

Catalin Voiniciuc, Leibniz Institute of Plant Biochemistry, Germany
George W. Haughn, University of British Columbia, Canada  

Copyright: © 2019 Miart, Fournet, Dubrulle, Petit, Demailly, Dupont, Zabijak, Marcelo, Boudaoud, Pineau, Guénin, Van Wuytswinkel, Mesnard and PAGEAU. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Karine PAGEAU, University of Picardie Jules Verne, Amiens, 80039, France, karine.pageau@u-picardie.fr