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Tryfona T, Pankratova Y, Petrik D, Rebaque Moran D, Wightman R, Yu X, Echevarría-Poza A, Deralia PK, Vilaplana F, Anderson CT, Hong M, Dupree P. Altering the substitution and cross-linking of glucuronoarabinoxylans affects cell wall architecture in Brachypodium distachyon. New Phytol 2024; 242:524-543. [PMID: 38413240 DOI: 10.1111/nph.19624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 02/05/2024] [Indexed: 02/29/2024]
Abstract
The Poaceae family of plants provides cereal crops that are critical for human and animal nutrition, and also, they are an important source of biomass. Interacting plant cell wall components give rise to recalcitrance to digestion; thus, understanding the wall molecular architecture is important to improve biomass properties. Xylan is the main hemicellulose in grass cell walls. Recently, we reported structural variation in grass xylans, suggesting functional specialisation and distinct interactions with cellulose and lignin. Here, we investigated the functions of these xylans by perturbing the biosynthesis of specific xylan types. We generated CRISPR/Cas9 knockout mutants in Brachypodium distachyon XAX1 and GUX2 genes involved in xylan substitution. Using carbohydrate gel electrophoresis, we identified biochemical changes in different xylan types. Saccharification, cryo-SEM, subcritical water extraction and ssNMR were used to study wall architecture. BdXAX1A and BdGUX2 enzymes modify different types of grass xylan. Brachypodium mutant walls are likely more porous, suggesting the xylan substitutions directed by both BdXAX1A and GUX2 enzymes influence xylan-xylan and/or xylan-lignin interactions. Since xylan substitutions influence wall architecture and digestibility, our findings open new avenues to improve cereals for food and to use grass biomass for feed and the production of bioenergy and biomaterials.
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Affiliation(s)
- Theodora Tryfona
- Department of Biochemistry, School of Biological Sciences, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Yanina Pankratova
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, NW14-3212, USA
| | - Deborah Petrik
- Department of Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Diego Rebaque Moran
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, SE-106, Sweden
- Centro de Biotecnologia y Genomica de Plants (UPM-INIA/CSIC), Universidad Politecnica de Madrid, Pozuelo de Alarcon (Madrid), 28223, Spain
| | | | - Xiaolan Yu
- Department of Biochemistry, School of Biological Sciences, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Alberto Echevarría-Poza
- Department of Biochemistry, School of Biological Sciences, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Parveen Kumar Deralia
- Department of Biochemistry, School of Biological Sciences, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Francisco Vilaplana
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, SE-106, Sweden
- Wallenberg Wood Science Centre, KTH Royal Institute of Technology, Stockholm, SE-11, Sweden
| | - Charles T Anderson
- Department of Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, NW14-3212, USA
| | - Paul Dupree
- Department of Biochemistry, School of Biological Sciences, University of Cambridge, Cambridge, CB2 1QW, UK
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Tryfona T, Bourdon M, Delgado Marques R, Busse‐Wicher M, Vilaplana F, Stott K, Dupree P. Grass xylan structural variation suggests functional specialization and distinctive interaction with cellulose and lignin. Plant J 2023; 113:1004-1020. [PMID: 36602010 PMCID: PMC10952629 DOI: 10.1111/tpj.16096] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
Xylan is the most abundant non-cellulosic polysaccharide in grass cell walls, and it has important structural roles. The name glucuronoarabinoxylan (GAX) is used to describe this variable hemicellulose. It has a linear backbone of β-1,4-xylose (Xyl) residues that may be substituted with α-1,2-linked (4-O-methyl)-glucuronic acid (GlcA), α-1,3-linked arabinofuranose (Araf), and sometimes acetylation at the O-2 and/or O-3 positions. The role of these substitutions remains unclear, although there is increasing evidence that they affect the way xylan interacts with other cell wall components, particularly cellulose and lignin. Here, we used substitution-dependent endo-xylanase enzymes to investigate the variability of xylan substitution in grass culm cell walls. We show that there are at least three different types of xylan: (i) an arabinoxylan with evenly distributed Araf substitutions without GlcA (AXe); (ii) a glucuronoarabinoxylan with clustered GlcA modifications (GAXc); and (iii) a highly substituted glucuronoarabinoxylan (hsGAX). Immunolocalization of AXe and GAXc in Brachypodium distachyon culms revealed that these xylan types are not restricted to a few cell types but are instead widely detected in Brachypodium cell walls. We hypothesize that there are functionally specialized xylan types within the grass cell wall. The even substitutions of AXe may permit folding and binding on the surface of cellulose fibrils, whereas the more complex substitutions of the other xylans may support a role in the matrix and interaction with other cell wall components.
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Affiliation(s)
- Theodora Tryfona
- Department of Biochemistry, School of Biological SciencesUniversity of CambridgeCambridgeCB2 1QWUK
| | | | - Rita Delgado Marques
- Department of Biochemistry, School of Biological SciencesUniversity of CambridgeCambridgeCB2 1QWUK
| | - Marta Busse‐Wicher
- Department of Biochemistry, School of Biological SciencesUniversity of CambridgeCambridgeCB2 1QWUK
| | - Francisco Vilaplana
- Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and HealthKTH Royal Institute of TechnologyStockholmSE‐10691Sweden
| | - Katherine Stott
- Department of Biochemistry, School of Biological SciencesUniversity of CambridgeCambridgeCB2 1QWUK
| | - Paul Dupree
- Department of Biochemistry, School of Biological SciencesUniversity of CambridgeCambridgeCB2 1QWUK
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