Abstract text: Plant cell walls influence many aspects of plant growth, mechanics, and environmental responses. These wall functions are elegantly showcased in the dynamic movements and development of graminoid stomata. In these four-celled stomatal complexes, two guard cells flanked by two subsidiary cells enable rapid stomatal responses to environmental stimuli. Stomatal dynamics rely on different cell wall behaviors, with subsidiary cells undergoing persistent deformation and rod regions of guard cells showing minimal change in shape. Although microscopy has been conducted to reveal cell wall organization that may facilitate the quick movements of graminoid stomata, how individual wall polymers contribute to stomatal development and dynamics remain unknown. To address this, we are examining stomatal structure and function in cell wall mutants of Brachypodium distachyon generated with CRISPR and artificial microRNA approaches. Our results indicate that cellulose biosynthesis in guard cells is necessary for the normal development of mature stomatal complexes. We also found that stomatal structures remain unaffected in mutants with decreased feruloylation of xylan. Future efforts include measuring the kinetics of stomatal responses using both confocal microscopy and the LI-6800 photosynthesis system. This research highlights how cell wall characteristics aid in the development of graminoid stomata and their responses to environmental stimuli.