Dissecting the Role of TOL3,6 and 9 in Endosomal Trafficking

Every living cell relies on a precisely coordinated transport system to maintain its diverse functions. This intracellular transport system ensures that the right proteins arrive at the right place at the right time and determines which molecules go where and when damaged or no longer needed components are broken down. In plant cells, this logistics system is particularly versatile. It not only influences fundamental processes such as cell growth and cell division, but also enables rapid adaptation to changing environmental conditions such as drought stress, cold, or pest infestation. Despite their fundamental importance, many details of these cellular transport pathways are still not fully understood. This research project focuses on so- called TOL proteins (TARGET OF MYB1-LIKE), which perform important tasks in the organization of cellular transport pathways in the model plant Arabidopsis thaliana. Until now, it was assumed that these proteins were mainly involved in sorting membrane proteins destined for degradation towards the vacuole. However, recent findings show that certain TOL proteins, in particular TOL3, TOL6, and TOL9, are significantly more versatile. Plants lacking these three proteins not only show disturbances in transport to the lytic vacuole, but also defects in transport to storage organelles, in secretion, and in the degradation of damaged cell components by autophagy. The aim of this project is to investigate the individual functions of these TOL proteins in detail and to clarify their role in the various transport pathways. Particular attention is being paid to TOL3, whose cellular distribution, interaction partners, and functional domains are being investigated. State-of-the-art methods from genetics, biochemistry, and novel imaging techniques are being used for this purpose. Microscopic techniques enable the precise localization of the proteins and the analysis of their interactions with known transport complexes. Genetic crosses and pharmacological treatments help to better understand the respective contributions of TOL proteins to specific transport pathways. This project sheds light on fundamental mechanisms of cellular logistics in plants, which have been little researched to date. In the long term, the findings can be used to specifically influence the cellular transport network, with possible applications in plant breeding, for example to improve stress tolerance and yield.