Cell size control during stomatal development in Arabidopsis

Xinyu Zhang, Robert Sablowski
Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK

Stomata, formed by two guard cells, regulate the movement of carbon dioxide and water across the leaf surface. The size of guard cells is physiologically important because it affects the balance between carbon assimilation and water loss. Although the development of stomata has been intensively studied, the regulation of stomatal size remains unclear. To address this question, we used long-term, quantitative time-course imaging. Our results support the idea that guard cell size is regulated cell-autonomously. Cell size variability diminished over successive stages of stomatal development, indicating one or more size-dependent steps. We also established that the final size of guard cells is independent of the initial size of their progenitor cells, suggesting that guard cell fate is associated with a target cell size. Current work aims to identify steps in stomatal differentiation that may be linked to cell size and to test whether mechanisms that are known to control cell size in meristem cells interact with regulators of stomatal development. Our research has long-term potential in optimising stomatal size and improving water use efficiency for climate-resilient plants.