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Two conifer GUX clades are responsible for distinct glucuronic acid patterns on xylan

Published version
Peer-reviewed

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Authors

Lyczakowski, Jan 
Yu, li 
Terrett, O 
Fleischmann, Christina 
Temple, Henry 

Abstract

Wood of coniferous trees (softwood), is a globally significant carbon sink and an important source of biomass. Despite that, little is known about the genetic basis of softwood cell wall biosynthesis. Branching of xylan, one of the main hemicelluloses in softwood secondary cell walls, with glucuronic acid is critical for biomass recalcitrance. Here, we investigate the decoration patterns of xylan by conifer GlucUronic acid substitution of Xylan (GUX) enzymes.

· Through molecular phylogenetics we identify two distinct conifer GUX clades. Using transcriptional profiling we show that the genes are preferentially expressed in secondary cell wall forming tissues. With in vitro and in planta assays we demonstrate that conifer GUX enzymes from both clades are active glucuronyltransferases.

· Conifer GUX enzymes from each clade have different specific activities. While members of clade one add evenly spaced GlcA branches, the members of clade two are also capable of glucuronidating two consecutive xyloses Importantly, these types of xylan patterning are present in softwood.

· Since xylan patterning might modulate xylan-cellulose and xylan-lignin interactions, our results further the understanding of softwood cell wall biosynthesis and provide breeding or genetic engineering targets that can be used to modify softwood properties.

Description

Keywords

conifers, glucuronic acid (GlcA), plant cell walls, softwood, xylan, Arabidopsis, Cell Wall, Glucuronic Acid, Plant Breeding, Tracheophyta, Xylans

Journal Title

New Phytologist

Conference Name

Journal ISSN

0028-646X
1469-8137

Volume Title

Publisher

Wiley
Sponsorship
Biotechnology and Biological Sciences Research Council (BB/L014130/1)
Biotechnology and Biological Sciences Research Council (BB/M015432/1)
Leverhulme Trust (RP2013-SL-008)
Biotechnology and Biological Sciences Research Council (1650974)
Biotechnology and Biological Sciences Research Council (BB/J014540/1)
This work was supported by the Leverhulme Trust Centre for Natural Material Innovation and by Biotechnology and Biological Sciences Research Council (BBSRC) of the UK as part of the OpenPlant Synthetic Biology Research Centre (Reference BB/L014130/1), Cambridge BBSRC-DTP Programme (Reference BB/J014540/1) and iCASE studentship (Reference BB/M015432/1). Work was also supported by a grant from the National Science Centre Poland awarded to JJL as part of the SONATINA 3 programme (project number 2019/32/C/NZ3/00392). We acknowledge the funding received from the New Zealand Ministry of Business, Innovation and Employment (MBIE) Endeavour Fund (Contract No. C04X1707, Fibre Grand Design) for supporting this work.