Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Vendredi 23 novembre 2012
IBIP Bât.7 à 11h
Trehalose-6-phosphate – a sugar signal linking plant development to primary metabolism
Max Planck Institut de physiologie végétale moléculaire – Golm, Potsdam Allemagne
Trehalose is a disaccharide sugar that is commonly found in bacteria, fungi and insects. It was once thought to be absent from flowering plants, apart from a few drought tolerant resurrection plants that accumulate trehalose to protect themselves from desiccation. This view changed in the last decade as genomic sequence data and studies of various mutants revealed that trehalose metabolism is not only universal in plants, but also essential for their normal growth and development. Trehalose is synthesised via the phosphorylated intermediate trehalose-6-phosphate (Tre6P). Plants with altered levels of this compound show strong morphological phenotypes, with alterations in leaf size, root growth, flowering time and inflorescence architecture. Using a new mass spectrometry-based assay, we found that the amount of Tre6P in plant tissues reflects changes in the levels of sugars, particularly sucrose, leading us to propose that Tre6P acts as a signal of sucrose status. We are now investigating both the upstream and downstream pathways of Tre6P signalling. Inhibitor studies showed that protein synthesis is required for the response of Tre6P to changes in sucrose content, and that phosphorylation and turnover of proteins could also be involved. The downstream response to changes in Tre6P levels depends on the organ or tissue in question. In source leaves, Tre6P appears to be part of a feedback loop that balances starch turnover with demand for sucrose from sink organs. In the vegetative shoot apex, Tre6P levels fluctuate in parallel with the diurnal supply of sucrose from the leaves, and we are currently investigating how such changes in Tre6P influence leaf development and the transition to flowering.
Contact : Christine Granier