Page 67 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

Wednesday, July 10

Dr. Lacey Samuels
University of British Columbia

“Building plant biomass: secondary cell wall
biosynthesis”

Abstract: The bulk of the plant biomass is made
up of secondary cell wall materials, including
cellulose, hemicelluloses, and lignin. With our
changing climate and requirement to reduced
dependence on fossil fuels, renewable
biopolymers of plant secondary cell walls
represent a promising source of bioproducts and
biofuels. Using a combination of molecular
genetics and advanced biological imaging, we
can manipulate the cellular and molecular machinery responsible for producing
secondary cell wall components. Beyond considering each component individually,
understanding how different components can influence each other’s biosynthesis
provides new insights into the coordination of secondary cell wall biosynthesis. For
example, cellulose production is sensitive to changes in the surrounding hemicelluloses
(glucuronoxylan). After polysaccharide deposition, the secondary cell wall is lignified
when monolignol precursors are exported to the cell wall where laccases and
peroxidases produce monolignol radicals that polymerize with radical coupling. Our
understanding of the lignification process is changing from active transport of
monolignols by unknown xylem cells, to a coordinated activity in which monolignols
diffuse from defined cell populations during xylem development. Diffusion is driven down
a concentration gradient, when monolignols are consumed by laccases and
peroxidases in the cell wall. Within secondary cell walls, regions like cell corners and
middle lamella have unique chemistries and functions, as well as distinct subsets of
laccases and peroxidases. Knocking out these combinations of laccases and
peroxidases changes lignification patterns. In addition to advancing basic biology,
defining these cell populations and oxidative enzymes that contribute to lignification
opens new opportunities for lignin manipulation.

Bio: Professor Samuels has a B.Sc. in Neurobiology from McGill University in Montreal, and a
Ph.D. in Botany, from the University of British Columbia in Vancouver, BC., Canada. She did
post-doctoral studies at the University of Colorado, Boulder, USA and at UBC Vancouver, where
she has been a faculty member since 2000. Professor Samuels initiated the UBC node of the
graduate teaching training network called the Centre for the Integration of Research, Learning,
and Teaching (CIRTL). She is Academic Director of the Bioimaging Facility, a campus-wide light
and electron microscopy shared research facility, and a member of the UBC Bioproducts
Institute. The goal of Samuels’ research is to integrate plant cell biology and biochemistry to
discover how plant cells produce valuable renewable resources.

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