Research Associate Complex Carbohydrate Research Centre Athens, Georgia
Body of Abstract: The secondary cell wall is a complex and dynamic structure predominantly composed of complex polysaccharides, including an abundance of cellulose and hemicellulose. These different polysaccharides are further interconnected with lignin through diverse chemical interactions giving rise to a hierarchical three-dimensional structure. Cell wall organization acquires significance in the context of valorization of biomass into high value products and novel biomaterials. The multilayered and characteristic relative positioning of different polysaccharides resulting from the diverse chemical decorations on polysaccharide backbones influences both their mechanical properties and the energy inputs required for valorization. Xylans are a great model wall polymer for synthetic biology-based modification and they are easy to analyze and abundantly present in the secondary cell walls of woody tissues. Xylans found in poplar trees are short polymers with a backbone of five carbon xylose sugars that can be further modified by chemical decorations such as glucuronic acid, and 4-O-methylglucuronic acid, and O-acetyl substitutions. These substituents are present in precise numbers at regular spacing thus forming domains which facilitate diverse interactions with other polysaccharides. Our lab’s goal is to use Poplar as a chassis for the creation of different cell wall morphotypes, with an emphasis on xylan, through specifically targeting different carbohydrate regulatory pathways. We hypothesize that the mechanisms plants utilize to determine and or dictate the spacing of these domains are shaped by the structure and actions of enzymes that modify the xylan backbone at precise positions and regular intervals. These enzymes are potential genetic targets for alteration of the xylan chemical decorations via synthetic biology approaches developed using high resolution transcriptional analyses, with the goal of modulating both mechanical and chemical properties, ultimately creating trees with different cell wall morphotypes.