Thèse Organisation et Dynamique des Réseaux de Membranes Tubulaires Régissant le Trafic Sécrétoire chez les Plantes H/F - 33

Établissement : Université de Bordeaux
École doctorale : Sciences de la Vie et de la Santé
Laboratoire de recherche : Laboratoire de Biogenese Membranaire
Direction de la thèse : Yohann BOUTTE ORCID 000000027555074X
Début de la thèse : 2026-10-01
Date limite de candidature : 2026-05-20T23:59:59

Membrane trafficking is a fundamental process in eukaryotes, essential for the transport of proteins, lipids, and other molecules between cellular compartments. In plants, it plays a key role in many biological processes, including development, reproduction, hormone distribution, nutrient uptake, and immune responses. Biosynthetic trafficking begins in the endoplasmic reticulum (ER), continues through the Golgi apparatus, and culminates at the trans-Golgi network (TGN), where proteins are sorted to their final destinations such as the plasma membrane or the vacuole. Recent studies have revealed the existence of a dynamic tubular network, the plant ERGIC, which is involved in transport between the ER and the Golgi and in the formation of new Golgi structures. The TGN, also organized as a tubular network, supports both secretory and endocytic trafficking.
The presence of tubular networks on both sides of the Golgi raises important questions about their interactions, spatial organization, and roles in cargo sorting. This project aims to elucidate the structure, dynamics, and relationships between pre- and post-Golgi tubular networks using super-resolution microscopy, to identify the molecular actors involved through proteomic and lipidomic approaches, and to understand how these networks influence plant development and adaptation to environmental conditions.

Membrane traffic is a fundamental cellular process in eukaryote that involves the movement of proteins, lipids, and other molecules between different membrane compartments. In plants, membrane traffic plays important roles in various critical processes for plant growth and development, including seed development, reproduction, hormone distribution, nutrient uptake, and immune responses. Biosynthetic trafficking starts from the endoplasmic reticulum (ER) where approximately one-third of proteins are synthesized. These cargo proteins are generally received by the Golgi apparatus and reaches the post-Golgi station called trans-Golgi network (TGN) where cargo proteins are sorted to appropriate vesicles to their destinations, including the plasma membrane (PM) and vacuoles. In addition to studying vesicles, our group recently demonstrated that ER-to-Golgi trafficking relies on a highly dynamic tubular membrane network called the plant ERGIC. This network interacts with the ER and the Golgi, stabilizing in the vicinity of the latter and creating a new Golgi precisterna in a lipid-dependent manner (Fougère, Grison, et al., 2025). Preliminary results indicate that plant ERGIC interacts not only with the ER and the Golgi, but also with many other intracellular compartments including the TGN. The plant TGN hosts both secretory and endocytic trafficking and is thus capable of handling anterograde and retrograde transport within a single organelle of exquisite complexity that exhibits multiple identities. The TGN is also a tubular membrane network located on the post-Golgi side. Thus, tubular networks are present on both sides of the Golgi: the ERGIC on the pre-side and the TGN on the post-side, with the stack form of the Golgi in between. Do the ERGIC and TGN interact directly, bypassing the Golgi? The way the web of tubular networks at the pre- and post-Golgi sides orchestrates the generation, organization, connection, and maturation of intracellular compartments, as well as the sorting of various cargo proteins to the plasma membrane (PM), vacuoles, endosomes, and other organelles, remains a mystery. To solve this mystery, we must overcome the lack of resolution in conventional microscopy to understand how membrane tubular networks dynamically relate to each other, acquire their identity and how they sort a variety of cargo proteins to different destinations.

In this project, the student will aim at participating to decipher: 1) What is the exact structure of pre- and post-Golgi tubular networks, how they are spatially arranged between each other and in relation to other compartments, as well as how do they behave dynamically, this will be addressed by super-resolution microscopy, 2) What are the molecular actors (proteins and lipids) playing a role in this intricated web of membrane tubules, this will be performed through a proteomic and lipidomic screen, 3) How the web of tubular networks influence plant development and adaptation to environmental pressures.

The student will benefit from a unique combination of expertise in super-resolution 3D live imaging of TGN subdomains and lipid analytical biochemistry. The PhD student will be supervised by the group leader Yohann Boutté and experienced post-docs already working in Yohann Boutté' team.

Super-resolution microscopy, expansion microscopy, STED microscopy, lipid biochemistry, lipid analytical methods, cloning, transformation