Secret of plant dietary fiber structure revealed

Date:
September 17, 2020
Source:
University of Queensland
Summary:
Researchers have uncovered the mechanics of how plant cell walls
balance the strength and rigidity provided by cellulose with its
ability to stretch and compress. This discovery helps explain
how plant structures can range from floppy grasses to hard wood
trees and is important for understanding dietary fiber properties
in nutrition. The findings also have applications in medicine,
agriculture and a range of other industries.



FULL STORY ==========================================================================
The secret of how fibre shapes the structure of plant cell walls has
been revealed, with potentially wide-ranging applications ranging from nutrition and health to agriculture.


========================================================================== Researchers from The University of Queensland and KTH Royal Institute
of Technology in Sweden have uncovered the mechanics of how plant cell
walls balance the strength and rigidity provided by cellulose with its
ability to stretch and compress.

UQ Director of the Centre for Nutrition and Food Sciences Professor Mike
Gidley said the team identified that a family of cell wall polymers -- hemicelluloses -- played a critical role in balancing the need for
rigidity with the flexibility to bend without breaking.

"This discovery is important for understanding dietary fibre properties
in nutrition, but also for applications in medicine, agriculture and a
range of other industries," Professor Gidley said.

"Plants don't have a skeleton, and their structures can range from soft,
floppy grasses to the majestic architecture of a Eucalypt tree, with the
key differences lying in their cell wall fibre structures." The diversity
of plant structures results from the three core building blocks of plant
fibre -- cellulose, hemicellulose and lignins -- in the plant cell walls.



========================================================================== "Lignins provide the water-proofing in woody fibre and cellulose is the
rigid scaffolding material in almost all plant types, but the mechanical function of hemicellulose was something of a mystery," Professor Gidley
said.

Professor Gidley and Dr Deirdre Mikkelsen, in collaboration with Dr
Francisco Vilaplana at KTH's Wallenberg Wood Science Centre, experimented
with two major components of hemicellulose -- with dramatic effect.

"We tested the properties of cellulose when adding different proportions
of the two components, and found that 'mannans' improved compression while 'xylans' drastically increase its stretchiness," Dr Mikkelsen said.

"We generated modified cellulose material in the laboratory that could
be stretched to twice its resting length -- the equivalent to watching a
wet sheet of paper being stretched to double its length without tearing."
The team said its discovery had many applications, including in wound
care and in the texture of plant foods.

"This information is also of interest for gut microbiome research in understanding more about how plant cells walls, or fibre, break down in
the gut," Professor Gidley said.

"Complex plant fibre is already processed for low value applications,
but high value materials are usually made from pure (bacterial) cellulose.

"Our work creates the basis for a new cellulose chemistry in which xylans
and mannans are added to make composites with useful properties.

"This means new possibilities for developing better, environmentally- sustainable plant-based materials, as well as selecting natural plant
fibres with desirable properties in agriculture and food."

========================================================================== Story Source: Materials provided by University_of_Queensland. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jennie Berglund, Deirdre Mikkelsen, Bernadine M. Flanagan,
Sushil Dhital,
Stefan Gaunitz, Gunnar Henriksson, Mikael E. Lindstro"m,
Gleb E. Yakubov, Michael J. Gidley, Francisco Vilaplana. Wood
hemicelluloses exert distinct biomechanical contributions to
cellulose fibrillar networks.

Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-18390-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200917105352.htm

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