Integrated Molecular, Dynamic Imaging, and Modeling Analysis of Stomatal Guard Cell Walls

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This project seeks to determine how the carbohydrate-based cell walls of guard cells dynamically change shape to control stomatal pore size, thus allowing plants to control carbon dioxide (CO2) uptake and water loss. Stomata are small openings in the surfaces of plants that regulate the photosynthetic conversion of CO2 into plant biomass, which serves as a renewable source of food, materials, and bioenergy. A deeper understanding of cell wall structure, mechanics, and dynamics in stomatal guard cells will help identify plants that can more efficiently use water, a major limiting factor in global agricultural production. The computational image analysis and modeling tools that will be developed in this project will provide scientists with new ways of interpreting and understanding experimental data. Because stomatal guard cells are an amazing example of cellular engineering by plants and are accessible and observable by scientists of all ages, a learning module will be developed and deployed that allows 4th through 8th graders to observe stomatal dynamics first-hand and challenges them to construct and optimize functioning macro-scale models of stomatal guard cells, helping to inspire future scientists and engineers. This project will also train two PhD students and a research associate in interdisciplinary research skills that cross the boundaries of biology, computer and information science, and engineering.In plants, stomatal guard cells function as dynamic gatekeepers that control CO2 and water flux to maintain homeostasis. To control transpiration and photosynthesis, stomatal development, morphology, and mechanics are tightly regulated. However, two large gaps exist in our knowledge of how stomata develop and function. First, stomatal pores form via controlled separation of sister guard cells, but how this is accomplished is unknown. Second, the walls of guard cells must be highly flexible to enable repeated stomatal opening and closing, but strong enough to withstand the enormous turgor pressure that drives their deformation. How guard cell walls are molecularly constructed to meet these competing requirements remains largely undefined. This project will analyze the molecular and mechanical requirements for stomatal pore formation, and the dynamic molecular architecture of guard cell walls that underlie their unique mechanical properties, using a complementary set of approaches including molecular genetics, high-resolution microscopy, and computational image analysis. The data and insights gained from these analyses will be used to construct computational mechanical models of guard cell walls that can be iteratively refined with new experimental results, ultimately resulting in the ability to predict guard cell dynamics across a range of species, wall compositions, and signaling inputs.