Tues Sept 3rd // Investigating Suberin Biosynthesis in Poplar: Candidate Genes and Chemical Composition

Meghan Rains, PhD student
Algoma University / Queen's University

Pathogens, climate change, and pollution represent important stressors that plants face continuously. To better prepare for a changing terrestrial landscape, we must understand how plants adapt and cope with various environmental stressors. The plant cuticle and suberized cells (cork) are among the critical adaptations that plants developed when they moved from an aqueous environment to land. These cell wall-specific extracellular lipid barriers provide the first line of defense against pathogens and control water exchange. The cuticle covers most aerial plant surfaces and is composed of a polymer of fatty acids and waxes. The periderms of roots, tubers, and tree bark, contain waxes and suberin –an esterified network of glycerol and fatty acid derivatives that is bound to a lignin-like polymer. Although structural models have been inferred from chemical depolymerizations, the insoluble nature of these polymers makes analyses challenging, and consequently, the native structure of suberin remains unclear. Much of the current research on suberin biosynthesis has focused on the model plant Arabidopsis thaliana. However, the complete pathways have not yet been fully characterized, and it is unclear how knowledge derived from Arabidopsis translates to woody tree periderms. This dissertation work used a combination of chemical and molecular approaches to identify candidate genes for suberin biosynthesis and to investigate the structure of the polyester using the model tree, Populus trichocarpa (Poplar). The results from this research further our understanding of suberin structure in tree bark, establish improved methodologies, and generate hypotheses for future targeted studies.