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Breaking Down Walls for a Greener Tomorrow

Plant cells, the building blocks of plants, are encapsulated in strong walls referred to as “cell walls.” Cell walls, specific to the kingdom Plantae, are integral to plant growth and development, comprising three carbon-abundant polymers: cellulose, hemicellulose, and lignin, referred to as “lignocellulosic biomass” constitute the majority of dry plant biomass. These sugar-rich cell walls can be used to produce biofuels. Biofuels serve as sustainable alternatives to fossil fuels because the carbon dioxide released into the atmosphere from burnt biofuels is recaptured by plants during the photosynthesis process. However, releasing sugars from cell wall polymers remains a challenge. That’s where my research comes in. I study specific components of cell walls called “hydroxycinnamic acids.” Hydroxycinnamic acids are mono-phenolic intermediates in the lignin biosynthetic pathway, including major species such as ferulic acid and p-coumaric acid. Hydroxycinnamic acids abundantly decorate grass cell wall polymers, namely xylan (the major hemicellulose in grasses), and lignin. Sparse hydroxycinnamoylation occurs in dicots and other monocots as well. Our understanding of the biological functions of hydroxycinnamic acid substitutions is incomplete. What is known so far is that the ferulic acid decorations can crosslink xylan, thereby strengthening cell walls. The cross-linking property of ferulic acid is associated with reduced suitability for biofuel production. I am engineering rice plants as a model to alter the hydroxycinnamic acid content in cell walls by targeting the enzymes that substitute these acids on the cell wall polymers. One of the main goals of this project is to make grasses more amenable to biofuel production. The genomic synteny of grasses will allow the application of knowledge gained from this study to less tractable but important bioenergy crops like switchgrass.