Endodermis to Exodermis: Are we on the same page?

The root system anchors the plant and its cells absorb water and nutrients. As plants are sessile organisms, controlling external compound entry is essential for plant survival. In vascular plants, the endodermis is the innermost root ground tissue cell layer that controls entry to the plant vasculature by formation of a barrier for free diffusion of solutes from the soil. Moreover, many plant species also contain an exodermis layer which also acts as a barrier. The exodermis is located internal to the epidermis layer. In a differentiated state, cells of both layers contain a Casparian strip. In Arabidopsis the Casparian strip is a lignin-like structure that is deposited as a ring in the transverse section of cells and around the secondary cell wall. Here, we explore whether endodermis and exodermis differentiation are regulated similarly. We use the tomato root as a model system to address endodermis and exodermis differentiation at the phenotypic and molecular level. Moreover, we address whether there are differences among species that grow in different environments similar to the environment in which their growth has been adapted.