Plant cell walls: Emerging targets of stomata engineering to improve photosynthesis and water use efficiency

Stomata are tiny pores on leaf surfaces essential for plant transpiration and photosynthesis. As gatekeepers that mediate gas exchange between plants and the atmosphere, stomata exert a major influence on global carbon and water cycles. The shape and function of stomata are physically constrained by stomatal walls. Compared to the extensively studied genetic mechanisms of stomatal development and guard cell signaling, recent progress is only beginning to uncover the role of plant cell walls in stomatal development and dynamics. In this review, we summarize the research on cell walls of the kidney-shaped stomata from dicots and the dumbbell-shaped stomata from grasses. As the dynamic response of grass stomata is closely linked to its anatomical features that are limited by cell walls, we discuss the potential of plant cell walls as crucial targets for crop engineering to enhance carbon assimilation and water use efficiency.