Dissecting the roles of monolignol supply and oxidative enzymes in Arabidopsis thaliana lignification
department or school: Science, Faculty of
department or school: Botany, Department of
data provider: DSpace
degree campus: UBCV
creator: Kuo, Chak Chung
issued: 2024-01-10T16:59:30Z
issued: 2023
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: Lignin is a rigid, hydrophobic polymer that strengthens the cell wall of supportive fibres and water-conducting vessels in vascular plants. Four main stages of lignification include: (1) monolignol production in the cytosol via the phenylpropanoid pathway, activated by MYB58 and MYB63 transcription factors; (2) monolignol diffusion into the cell wall; (3) monolignol radicalization by laccases (LACs) and/or peroxidases (PRXs); and (4) radical coupling of monolignols into polymeric lignin. Disrupting monolignol production or mutating oxidative enzymes often leads to improper plant development or dwarfism, suggesting that the quantity and location of lignin in the cell wall must be tightly regulated. It remains unclear how plants balance monolignol production and oxidative enzyme activity to coordinate proper lignification and plant development. In this study, Arabidopsis plants that overexpress MYB63 in xylem vessels and interfascicular fibres have increased stem lignin content without growth penalty. This suggests that a moderate increase in metabolic flux through the phenylpropanoid pathway leads to hyperlignification in lignifying cell types that possess the necessary molecular machinery for lignification. To understand how oxidative enzymes in distinct cell wall domains contribute to lignification, higher order mutants of LACs and PRXs were created with CRISPR/Cas9. Mutating genes encoding secondary cell wall-localized LAC4, LAC17, and PRX72 led to more irregular vessels and less stem lignin than the lac4-2 lac17 double mutant without additional growth penalty; mutating genes encoding cell corner/middle lamella-localized LAC4 and PRX64 led to shorter stems compared to the lac4-2 single mutant. This suggests that vessel irregularity does not contribute to lignin modification-induced dwarfism. The ability to modulate the quantity and distribution of lignin without growth penalty will provide insights into engineering low-lignin plants for more efficient conversion o…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/87192
note: DISSECTING THE ROLES OF MONOLIGNOL SUPPLY AND OXIDATIVE ENZYMES IN ARABIDOPSIS THALIANA LIGNIFICATION by Chak Chung Kuo B.Sc., The University of British Columbia, 2021 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in The Faculty of Graduate and Postdoctoral Studies (Botany) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) December 2023 © Chak Chung Kuo, 2023 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the thesis entitled: Dissecting the roles of monolignol supply and oxidative enzymes in Arabidopsis thaliana lignification submitted by Chak Chung Kuo in partial fulfilment of the requirements for the degree of Master of Science in Botany Examining Committee: Dr. Anne Lacey Samuels, Professor, Department of Botany, UBC Supervisor Dr. Shawn Mansfield, Professor, Departments of Botany and Wood Science, UBC Supervisory Committee Member Dr. Simone Castellarin, Professor, Wine Research Centre, UBC Supervisory Committee Member Dr. Abel Rosado, Associate Professor, Department of Botany, UBC Additional Examiner iii Abstract Lignin is a rigid, hydrophobic polymer that strengthens the cell wall of supportive fibres and water-conducting vessels in vascular plants. Four main stages of lignification include: (1) monolignol production in the cytosol via the phenylpropanoid pathway, activated by MYB58 and MYB63 transcription factors; (2) monolignol diffusion into the cell wall; (3) monolignol radicalization by laccases (LACs) and/or peroxidases (PRXs); and (4) radical coupling of monolignols into polymeric lignin. Disrupting monolignol production or mutating oxidative enzymes often leads to improper plant development or dwarfism, suggesting that the quantity and location of lignin in the cell wall must be tightly regulated. It remains unclear how plants balance monolignol production and oxidative enzyme activity to coordinate proper lignifi…
has type: Thesis/Dissertation
date issued: 2024-05
is shown at: 10.14288/1.0438616
language: eng
degree discipline: Botany
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Samuels, Anne Lacey, 1962-
type: Text
identifier URI: http://hdl.handle.net/2429/87192