A Golgi-released subpopulation of the trans-Golgi network mediates protein secretion in Arabidopsis ($)

The plant trans-Golgi network (TGN) plays the role of early endosomes and acts as hub for the both secretory and vacuolar trafficking pathways. Two types of TGN, GA-TGN (Golgi-associated TGN) and GI-TGN (Golgi-released independent TGN), have been observed in plants. Here, Uemura et al. explore the cellular and physiological roles of GI-TGN. They show that GI-TGNs are involved in the protein secretory pathway and facilitate the transport of R-SNARE VAMP721 towards the plasma membrane, mediated via the SYP4-dependent secretory pathway that is also involved in extracellular defense against powdery mildew pathogens. Their model suggests that “the GA-TGN matures first into the GI-TGN and then into secretory vesicles by increasing the abundance of VAMP721-dependent secretory pathway components”. (Summary by Arif Ashraf) Plant Physiol. 10.1104/pp.18.01228