Abstract: Phloem is the vascular tissue in plants - responsible for transporting sugars from source to sink. It is well established that osmotic currents drive the flow of sap through phloem vessels. The energy cost of phloem transport is primarily in the maintenance of the concentration gradient driving these osmotic currents. The bioenergetic force behind the loading of sugars and amino acids into phloem is generated by proton gradients at the plasma membrane of specialised phloem-loading cells. The proton gradient across the plasma membrane is maintained by actively pumping protons from the cytosol to the apoplast. This allows cells to use proton-coupled plasma membrane symporters to import sugars up their concentration gradients but down the proton gradient and into the phloem. From there the osmotic currents carry them to where they are needed within the plant.

Despite its essential role in vascular plant growth, the specifics of phloem cell metabolism remain unclear. Maintaining these concentration gradients is likely to be an energy bottleneck in plant growth but there is still uncertainty in the source and transfer of energy in companion cells. Combining cell-specific transcriptome data with a computational model of metabolism within phloem cells, we explore the potential metabolic interactions between cells to identify the main contributors to this energy bottleneck and the best targets to resolve it and increase plant growth.

Bio: After completing my undergrad and honours In maths at ANU, I started a PhD in mathematical biology modelling intracellular calcium signals with Edmund Crampin and Vijay Rajagopal at the University of Melbourne. I’m currently working on models of core metabolism in phloem tissue and roots with the Sweetlove Group at Oxford University.