Environmental Transformations and Interactions
Making Cell Walls Thicker May Not Make Better Bioproducts
A study pulls back the curtain on the inner workings of plants to understand how genetically engineering changes to cell walls affects the growth of the plant as well as the degradation of plant components.
Studying the rigid secondary cell walls of a small flowering plant called Arabidopsis at the molecular level is helping scientists determine how to make bioproduct crops easier to process. (Photo by pkujiahe | iStock)
The Science
A major barrier to using plants as bioproducts is the difficulty in releasing carbon from cell walls, where large amounts are stored. One way to resolve this issue is to genetically alter cell wall composition, but it is difficult to determine how well the effects of this genetic engineering work. That is because most methods to study cell wall structure require the cells to be pretreated in some way, which disrupts the very structure being studied. Now, with a goal of developing better bioproduct crops, a multi-institutional team of scientists has used an advanced approach called solid-state nuclear magnetic resonance to directly monitor the structural details of plant cell walls at the molecular level without significantly altering those cell walls.
The Impact
The urgent requirement to reduce carbon emissions from fossil fuels is offset by the growing global demand for carbon-based fuels, chemicals, and materials. Plants, particularly those that have a carbon-rich secondary cell wall that provides rigidity, could meet both needs. Unfortunately, the complex structure and arrangement of components in this secondary cell wall mean that the carbon stored there is difficult to access in an economical and sustainable way. Finding an approach to directly study engineered changes in plant cell walls, then, becomes imperative for enabling a robust bioeconomy.
Summary
A multi-institutional team of scientists sought to understand the molecular structure and formation of plant cell walls by genetically engineering the polymer structure of the cell walls. They started with a small flowering plant called Arabidopsis, which is often used to study biological processes. This plant genus had been genetically engineered to produce a thicker secondary cell wall. Using multi-dimensional solid-state nuclear magnetic resonance at EMSL, the Environmental Molecular Sciences Laboratory, a U.S. Department of Energy (DOE) Office of Science user facility, the scientists monitored the structure of the plant cell walls at the molecular level. Surprisingly, they discovered that thickening the cell wall caused other components of the cell to compete with each other. Instead of making the plant’s stored carbon easier to process, the thickening actually disrupted the cell wall’s architecture and affected plant growth. The team concluded that more research is needed before attempting to thicken the cell walls of trees or other bioenergy crops to avoid negative effects on plant growth.
Contacts
Jennifer Mortimer, University of Adelaide, jenny.mortimer@adelaide.edu.au
Yu Gao, Joint BioEnergy Institute, gaoyu88@gmail.com
Andrew Lipton, EMSL, andrew.lipton@pnnl.gov
Funding
This work was conducted as part of the DOE Office of Science’s Joint BioEnergy Institute. A portion of this research was conducted at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility, as part of a large-scale research award. The work was also supported by start-up funding from the University of California-Davis and the University of Adelaide in Australia.
Publication
Y. Gao, et al., “Elongated galactan side chains mediate cellulose–pectin interactions in engineered Arabidopsis secondary cell walls.” The Plant Journal 115, 529 (2023). [DOI: 10.1111/tpj.16242]