The size and shape of leaves are important agricultural traits that strongly influence crop yield. The growth of individual cells collectively determine leaf morphology, and a major challenge in biology is to understand how cellular constituents pattern the cell wall to influence local rates and directions of cell growth. This project focuses on discovering the growth control mechanisms of the outer layer of cells that form the leaf epidermis. The epidermis serves both as a waterproof layer that protects the leaf and as a growing biomechanical shell that influences the size and shape of the leaf. This project aims to understand how cell signaling and cytoskeletal patterning is controlled among adherent cells and how local growth can scale to influence tissue or whole leaf traits. The Broader Impact activities include interdisciplinary training for all members of the team (including undergraduates and high school students). A K-12 summer camp module will also be developed for the Young Nebraska Scientist Program.
The Arabidopsis leaf epidermal morphogenesis system is ideally suited for major breakthroughs. However, progress has been slow because of the lack of reliable phenotyping methods to define genetic pathways and analyze the non-intuitive biomechanical interactions that occur among the cytoskeleton, cell wall, and cell geometry. The interdisciplinary research team will create a new experimental and computational approach to discover how microtubule-dependent patterning of cellulose microfibrils drives polarized growth in the epidermis. The resulting computational models will make predictions about the how cells generate the spatial and temporal heterogeneities in the cell wall that drive interdigitated growth of these jig-saw-puzzle shaped cells. Importantly, biomechanical feedback control of the cell wall on the microtubule cytoskeleton is a general feature of plant development. The proposed research will generate data and create integrated computational models that reveal how cell wall stress patterns influence cortical microtubules and tissue morphogenesis.