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Phosphate signaling in plants: dynamic study of phosphate movements and gene induction kinetics

Final Report Summary - PHOSPHEURUS (Phosphate signaling in plants: dynamic study of phosphate movements and gene induction kinetics)

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.
The PhosphEurUS project goal was to improve our knowledge of the mechanisms triggered by the detection of phosphate by plants, through the development of new tools. Hélène Javot, from the CEA-Cadarache institution (France), was in charge of this project. She is currently working on phosphate signaling in Arabidopsis thaliana (in Laurent Nussaume’s laboratory at CEA Cadarache; The project was developed in close collaboration with a team of expert photo-chemists (A. Specht, Illkirch, France; Herbivo 2013) and with H. Javot’s previous host laboratory (Maria Harrison’s team, USA), where she worked for five years on the phosphate transport occurring during the symbiosis between plants and endomycorrhizal fungi.
Our first goal was to be able to follow, in living plants, the induction or repression of a set of phosphate-responding genes representative of local / systemic plant responses to phosphate starvation (Thibaud 2010, Hirsch 2010). During this project, about 20 Arabidopsis thaliana reporter lines expressing promoter-luciferase fusions have been generated. In addition, two luminescent reporter lines were generated for the study of phosphate regulation in the plant Medicago truncatula. These lines are now being used in different projects of our laboratory as well as by our collaborating partners.
Another technical barrier to progress in the field of phosphate-sensing studies was the lack of technical tools allowing researchers to control free phosphate fluctuations inside the cell, in a precise and time-resolved manner. Thanks to the collaboration with A. Specht, we developed a “caged-phosphate” compound for the controlled release of phosphate by light illumination in living cells (Herbivo 2013). Current efforts are focused on the in vivo application of this molecule.
This novel set of tools developed during the PhosphEurUS project joined traditional genetic and molecular biology analyses, to progress towards identifying new components in the phosphate detection signaling cascade. They will help us understand how the signal can be differentially transmitted to the different tissues of the plant. Our selective focus on different markers of the phosphate signaling pathway will provide tools for monitoring nutrient efficiency in crops, and will lead to innovative integrated strategies of plant production based on a more efficient use of fertilizer input.
Hirsch J, Misson J, Crisp PA, David P, Bayle V, Estavillo GM, Javot H, Chiarenza S, Mallory AC, Maizel A, Declerck M, Pogson BJ, Vaucheret H, Crespi M, Desnos T, Thibaud M-C, Nussaume L and Marin E. (2010) A novel fry1 allele reveals the existence of a mutant phenotype unrelated to 5'->3' exoribonuclease (XRN) activities in Arabidopsis thaliana roots. PLoS ONE. 6: e16724.

Thibaud, MC, Arrighi, JF, Bayle, V, Chiarenza, S, Creff, A, Bustos, R, Paz-Ares, J, Poirier, Y, Nussaume, L (2010). Dissection of local and systemic transcriptional responses to phosphate starvation in Arabidopsis. Plant J 64: 775-89.

Herbivo C, Omran Z, Revol J, Javot H, Specht A (2013) Synthesis and characterization of cell-permeable caged phosphates that can be photolyzed by visible light or 800 nm two-photon photolysis. Chembiochem. 14(17):2277-83.