Architecture and functions of stomatal cell walls in eudicots and grasses

• Background Like all plant cells, the guard cells of stomatal complexes are encased in cell walls that are composed of diverse, interacting networks of polysaccharide polymers. The properties of these cell walls underpin the dynamic deformations that occur in guard cells as they expand and contract to drive the opening and closing of the stomatal pore, the regulation of which is crucial for photosynthesis and water transport in plants. • Scope Our understanding of how cell wall mechanics are influenced by the nanoscale assembly of cell wall polymers in guard cell walls, how this architecture changes over stomatal development, maturation and ageing and how the cell walls of stomatal guard cells might be tuned to optimize stomatal responses to dynamic environmental stimuli is still in its infancy. • Conclusion In this review, we discuss advances in our ability to probe experimentally and to model the structure and dynamics of guard cell walls quantitatively across a range of plant species, highlighting new ideas and exciting opportunities for further research into these actively moving plant cells.