Linking Epidermis and Mesophyll Signalling. Anatomy and Impact in Photosynthesis.

The current project aims to explore the signalling pathways of epidermal development and their connection with mesophyll development and elucidate the impact on photosynthetic performance. We will combine plant signalling and physiology, integrating both disciplines with molecular biology and functional genomics methodologies. Stomatal pores on the leaf surface and a porous leaf mesophyll are prerequisites for effective plant gas exchange for photosynthesis and transpiration. The rate at which the stomata or mesophyll facilitate gas exchange is called conductance. The stomatal conductance (gs) depends on the size and density of the stomata, and the arrangement of the air spaces and other structural factors, including cell wall thickness and composition of the plasma and chloroplast membranes, determines the mesophyll conductance (gm). We believe that the coordination of the development of the stomata and the mesophyll structure is possible through signalling pathways to optimize potential gs and gm at the leaf level. With this, there is potential to improve water use efficiency by manipulating the relationship between the structures and, therefore, the conductance of these two tissues. Although the epidermal development, patterning, and inner anatomy of the leave have been well studied in the past years, they have barely been studied together. In this sense, the A. thaliana mutants stomagen and cdk8 are ideal for addressing this hypothesis. In these mutants, the stomata development is induced or repressed; for instance, CO2 exchange and photosynthesis may be affected.