HOW PROTEOMIC STUDIES HELP US TO UNDERSTAND ESSENTIAL ROLES OF AUTOPHAGY IN PLANTS
Résumé
In plant, leaf senescence is a long developmental process that is part of a developmental program that aims at controlling a gradual shift from anabolism to catabolism. Leaf senescence is characterized by the progressive degradation and clearance of chloroplasts. Macroautophagy is induced in plant in response to many stresses and in parallel with leaf senescence. While it works at maintaining leaf longevity during this process, its role in the degradation of macromolecules also contributes to nutrient recycling. Nutrients released through autophagy are then exported to be reused in growing parts of the plant. Our group showed that autophagy is responsible of 50% of the nutrient remobilization from source leaves to sink organs, especially under nutrient restriction. We showed that both C and N metabolisms are largely affected when autophagy is defective and that autophagy affects endomembrane recycling. Autophagy mutants display ER-stress phenotype. Our aim is now to study in deep how autophagy targets organelles and cargoes and to identify adaptors involved in specific autophagy. Proteomic studies have been performed that revealed proteins abnormally accumulated in autophagy mutants. Interactions of cargo candidates with the ATG8 protein is ongoing.