Uncovering the mechanisms of plant cell wall signalling and responses

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The plant cell wall surrounds and protects all plant cells. It is essential to everyday life for plants and for all ~7.7 billion people on Earth. Cell walls provide us with dietary fibre in the fruits, vegetables, and grains that we eat; yet there are increasing concerns that current food production rates might not meet future demands. Wood and other dried cell wall material is traditionally burned as a source of energy; today, interest continues to intensify in using plant biomass as a source for next-generation renewable biofuels, such as bioethanol derived from fermenting cell wall material. Cell walls also offer an exciting resource for environmentally-friendly and renewable materials; since the Canadian government's announcement that they will ban many single-use plastics starting in 2021, companies are looking to bio-plastics, which are often derived from cell wall material. Plant biology and biotechnology have excellent potential to address these pressing economic and environmental issues. In particular, the plant cell wall is an important target for improvement, either by traditional breeding or genetic modification. However, previous attempts to modify plant cell walls have exposed a critical gap in our understanding: plants perceive the status of the cell wall via largely unknown mechanisms, called “cell wall signaling” and the typical plant response to these signals is to limit growth. Therefore, cell wall modifications often cause yield penalties that render any cell wall “improvements” agriculturally and economically unviable. The long-term goal of the McFarlane lab is to discover how plants sense and respond to cell wall changes. This proposal leverages large-scale datasets that we previously generated to uncover new components of cell wall signaling. We will characterize the molecular mechanisms of these cell wall signaling components and track plant responses to these signals using a combination of plant genetics, molecular biology, biochemistry, quantitative live cell imaging, high-resolution electron microscopy, and computational analyses of these datasets. This work asks key questions, such as: What molecular components are required for cell wall signaling? How is cell wall signaling turned “on” or “off”? Do different cell wall changes activate the same signals? How do plants modify their cell walls in response to these signals? How much can we modify the cell wall before the plant responds? Does cell wall signaling affect other plant signaling pathways, such as immune responses or hormone signaling? By addressing these questions, we will develop the next generation of Canadian-trained scientists and expand foundational knowledge about cell wall signaling. Results from this research will provide insight into how best to improve plant productivity to address current and future challenges in Canada, such as advancing sustainable agriculture, enhancing food security, and developing next-generation biofuels and biomaterials.