Shapeshifters: Functional Interplays between Plant Cell Walls and Dynamic, Reversible Shape Changes in Plant Cells and Tissues

The three-dimensional shapes of plant cells help define both their biological functions and the morphologies of the tissues and organs they constitute. Many plant cells dynamically change shape: this occurs not only during the cell expansion that underlies plant growth, but also in mature cells that can deform either passively as plants are perturbed by environmental factors or actively to actuate movements that occur from cellular to whole-plant scales in response to intrinsic and external stimuli. Plant cells are encased in strong but often flexible cell walls, and wall mechanics define and constrain subcellular, cellular, and supracellular deformability. Reversible cell deformations can facilitate physiological responses, allowing plants to remain structurally robust and adapt to changing conditions while remaining rooted in place. The ability to observe and quantify the three-dimensional geometry, biomechanical properties, and dynamic shape changes of plant cells and their walls has evolved along with technical advances in microscopy and image capture, mechanical probing instrumentation, and quantitative data analysis and modelling. These advances are accelerating, promising a future wherein scientists will be able to measure, predict, and design plant cell deformations across four dimensions from nano- to macro-scales. Connecting the molecular architecture, geometric flexibility, and biomechanics of plant cell walls to plant development and physiology might reveal new pathways for optimising plant growth and productivity.