Environmental Science and Engineering Seminar

Stomata are pores on the epidermis of plants that facilitate the exchange of gases between the interior of the plant and the external environment. This is a fundamental process because it permits atmospheric carbon dioxide to perfuse into cell tissues that perform photosynthesis, but as a corollary, it also releases water vapor.  However, the consequences of gas-exchange extend far beyond the productivity of an individual plant, as transpiration and carbon sequestration have dramatic effects on ecosystem structure, global energy cycles, and are even capable of driving large shifts in climate.  We used genetic tools in Arabidopsis thaliana to alter the density and pattern of stomata on the epidermis and the physiological outcomes of those changes were quantified by leaf-level gas-exchange experiments, carbon isotope analysis, and confocal microscopy of leaf morphology.  Stomatal conductance (the rate of gas-exchange) could be modeled as a function of stomatal density and size (gsmax) and the responses to increasing atmospheric carbon dioxide could be scaled to these pore-level properties. Furthermore, genetic regulators of stomatal development were capable of driving organizational changes in leaf mesophyll tissues, thus altering photosynthetic potential. These results indicate that stomatal development is critical for determining the physiological capacity of the leaf and stomatal anatomy can be characterized to predict plant-environment interactions under past, current, and future regimes of atmospheric carbon dioxide.