Photosynthesis provides the stored energy and the molecular building blocks for life on Earth. Sugars also have hormone-like properties in plants that regulate growth, developmental processes such as flowering time, affect pathogen sensitivity, and contribute to cell cycle progression. Coordinating photosynthesis in a multicellular, sessile organism requires integration of external cues with metabolism and transport processes across diverse cellular and subcellular compartments. This depends on multiple carbohydrate sensing and signalling pathways. We aim to understand how rhythmic sugar signals are sensed and decoded by plant cells. In particular, we are interested in how sugar and light signals interact in the context of photoautotrophy. Our previous research has shown that sugars produced from photosynthesis contribute to entrainment of the Arabidopsis circadian clock (Haydon et al., Nature 2013). The precise signalling pathways by which this occurs are not yet known, largely due to the genetic recalcitrance of sugar signalling pathways in plants. We are using novel tools and assays to better understand these and other signalling pathways and the downstream transcriptional networks.