Because phosphate is a major component of all cells, a deficiency in this mineral can have a dramatic impact on the physiology of any living organism. Unfortunately, we still have a very partial understanding of the signaling pathways involved in the acquisition, detection and homeostasis control of this nutrient. This project aims to increase our understanding of the mechanisms triggered by the detection of phosphate by plants. A significant technical barrier to progress in this field is the lack of technical tools allowing researchers to measure and control free phosphate fluctuations inside the cell in a precise and time-resolved manner. This project offers to develop such tools, which could be applied to the study of plants as well as to animal cells. They will allow us, along with genetical and molecular biology analyses, to progress towards the identification of new components of the phosphate detection signaling cascade. It will also help us understand how the signal can be differentially transmitted to the different tissues of the plant. This application is presented by Hélène Javot, and follows her recent arrival at the CEA-Cadarache institution (France), to work on phosphate signaling in Arabidopsis thaliana (in Laurent Nussaume’s laboratory). It is developed in close collaboration with a team of expert photo-chemists and with H. Javot previous host laboratory (Maria Harrison’s team, USA), where she worked for the past five years on the phosphate transport occurring during the symbiosis between plants and endomycorrhizal fungi. The project will fully integrate physiological analysis with state-of-the-art techniques of imaging, photochemistry and molecular biology. By pinpointing to different markers of the phosphate signaling pathway, we will provide tools for monitoring nutrient efficiency in crops and lead to innovative integrated strategies of plant production based on more efficient use of fertilizer input.