Plants generate sugars in their leaves (sources) during photosynthesis, which subsequently need to be distributed amongst growing organs such as new, young leaves, flowers, stems and roots as well as storage organs such as potato tubers or fruits (sinks). This sucrose transport depends on the activity of sources and sinks that together determine the osmotic gradients driving vasculature sap transport, with different sources competing for the sucrose. In addition, transport is regulated via long distance signalling molecules that control the activity of cellular sucrose transporters, thereby impacting the relative balance between symplastic (direct cell-to-cell) and apoplastic (cell-to-wall-to-cell) transport routes. Over the course of their development, plants may profoundly change their sugar transport, for example when making storage organs such as tubers they redirect a large part of their sugar transport to these organs. Additionally, depending on environmental conditions, plants may make different decisions on where to invest their sugars, e.g. in flowers for sexual reproduction or rather tubers for asexual reproduction. Exactly how plants reach these decisions, and subsequently rewire their sugar transport remains incompletely understood.
Project
Goal of the current project is to develop detailed computational simulation models of plant sucrose transport, incorporating different involved cell types and tissues, cellular uptake and export transporters and their regulation by signalling factors, symplastic and apoplastic transport routes, and source and sink strength dependent vasculature fluxes. The aim is to obtain an understanding of how plants control the amount of sucrose going to tubers versus other plant organs, for example in the context of investing energy in vegetative reproduction via tubers versus sexual reproduction via flowering. The selected candidate will work in the group of Prof. Kirsten ten Tusscher at the Computational Developmental Biology group at Utrecht University.
The PhD position is part of a larger TTW project on potato yield and will be performed in collaboration with the group of Christian Bachem at Wageningen University. Experimental and bioinformatic data obtained in the experimental counterpart of the project will thus serve as input for the modeling, while modeling outcomes will be used to direct future experiments into promising directions. The project is aimed to start in the spring of 2019.
