Tonni Grube Andersen - Understanding cell-specific nutrient uptake and biotic interactions in plant roots

Despite living in to contrasting environments, plants can grow efficiently and interact with their surroundings. Both the above- and belowground organs can discriminate between inputs and provide distinctive - and highly localized - responses to (a)biotic stimuli. In addition, roots have a high degree of developmental plasticity and responds to physiological inputs, in contrast to the almost exclusively hard-wired growth processes in animals. Yet, from an agricultural point of view, we have limited knowledge of factors that govern belowground physiology, especially on a single cell level. Within roots, the vascular tissues are surrounded by a protective cell layer termed the endodermis. The cell walls of the endodermis contain hydrophobic suberin, which is deposited in a surprisingly similar manner across virtually all plant species. Intriguingly, endodermal cells adjacent to the water conducting xylem do not always undergo suberization, and are thus historically termed “passage cells” as they are believed to provide a low-resistance pathway for water uptake. Recently, we found molecular mechanism(s) responsible for formation of passage cells, as well as marker genes that highlight these cells in the model plant Arabidopsis thaliana. Our analyses indicate that passage cells, in combination with adjacent outer cells, form trans-cellular “funnels” that might be involved in bilateral communication with the rhizosphere. This novel insight can be useful as a model to study root interactions with the environment in unprecedented detail. This is likely to lead to the invention of agricultural tools that can be applied to optimize physiological root traits such as nutrient use efficiency and microbiome assembly.