Autophagy is an intracellular degradation process critical to eukaryotic life and indispensable for plant survival to a wide range of environmental stresses including drought, nutrient scarcity or attacks by various pathogens. Autophagy relies on the formation of specialized vesicles which engulf and deliver cell components to the lytic vacuole. The formation of autophagy vesicles is carried out by a group of dedicated proteins and hinges on intense remodelling events and on the remarkable capacity of an initial membrane, the phagophore, to assemble de novo, shape like a cup, expand while maintaining structure and function and re-shape to a complete vesicle. At this time, the molecular mechanisms underlying these events remain elusive in plants. Research has focused on the role of autophagy proteins but, despite AP biogenesis being a membrane-based process, the fundamental contributions of lipids to AP membrane formation, identity and activities have been largely unexplored. In this project, we address the fundamental question of how autophagy vesicles form and shape by exploring how lipids’ nature, dynamics and lateral heterogeneity instruct the phagophore structure, its protein composition and its functions. We will tackle 3 complementary objectives: 1) Reveal the dynamic lipid signature of the phagophore, 2) Elucidate the implication of lipids nature and repartition in the phagophore ultrastructure, 3) Decrypt the molecular mechanisms by which lipids interplay with ATG proteins to control autophagy activity and plant physiology. Overall the project will articulate an integrated vision of the molecular processes controlling autophagy and provide fundamental knowledge in our understanding of plant responses and acclimation to environmental changes.
