"In addition to maintaining homeostasis within their cells, multicellular organisms also need to control their inner, extracellular spaces between cells. In order to do so, epithelia have developed, bearing ring-like paracellular barriers, with specialised membrane surfaces facing either the environment or the inner space of the organism. In animals, such polarised epithelia use specialised protein assemblies, called tight junctions, to seal the extracellular space, which have been a topic of active research for decades. Plant roots need to extract inorganic elements from the soil. A plethora of transporters are expressed in plant roots, yet, as in animals, transporter action is contingent upon the presence of efficient paracellular (apoplastic) barriers. Therefore, an understanding of the development, structure and function of the root apoplastic barrier is crucial for mechanistic models of root nutrient uptake. The endodermis is the main apoplastic barrier in roots, but, in contrast to animals, molecular data about endodermal differentiation and function has been virtually absent. We recently gained insights into the factors that drive endodermal differentiation, largely due to efforts from my research team. Our work has led a foundation of mutants, markers and protocols that provide an unprecented opportunity to test the many supposed roles of the root endodermis. Our preliminary insights indicate that generally accepted views of endodermal function have been overly simplistic. The topic of this proposal is to develop better tools and much more precise molecular analysis of nutrient uptake, centered around the endodermis. I propose to investigate our specific barrier mutants with new tools that allow visualisation of changes in nutrient transport at cellular resolution. The results from this project will provide a new foundation for models of plant nutrition and help us to understand how plants manage, and sometimes fail, to extract what they need from the soil."