Retrograde transport in plants: Circular economy in the endomembrane system

The study of endomembrane trafficking is crucial for understanding how cells and whole organisms function. Moreover, there is a special interest in investigating endomembrane trafficking in plants, given its role in transport and accumulation of seed storage proteins and in secretion of cell wall material, arguably the two most essential commodities obtained from crops. The mechanisms of anterograde transport in the biosynthetic and endocytic pathways of plants have been thoroughly discussed in recent reviews, but, comparatively, retrograde trafficking pathways have received less attention. Retrograde trafficking is essential to recover membranes, retrieve proteins that have escaped from their intended localization, maintain homeostasis in maturing compartments, and recycle trafficking machinery for its reuse in anterograde transport reactions. Here, we review the current understanding on retrograde trafficking pathways in the endomembrane system of plants, discussing their integration with anterograde transport routes, describing conserved and plant-specific retrieval mechanisms at play, highlighting contentious issues and identifying open questions for future research.

Automated summary

The study of endomembrane trafficking is crucial for understanding cellular and organism functionality. Investigating endomembrane trafficking in plants is of particular interest due to its role in transporting seed storage proteins and secreting cell wall material. While the mechanisms of anterograde transport in plants have been extensively discussed, retrograde trafficking pathways have received less attention. This review summarizes the current understanding of retrograde trafficking in the endomembrane system of plants, discussing its integration with anterograde transport, describing retrieval mechanisms, highlighting contentious issues, and identifying future research questions.