Shrinkage and fragmentation of the trans-Golgi network in non-meristematic plant cells.

Golgi products are exported from the trans-Golgi network (TGN) where they are sorted and packaged into secretory and clathrin-coated vesicles. We have examined TGN cisternae in Arabidopsis root columella cells and in maize basal endosperm transfer cells by electron microscopy/tomography. In these cell types, sizes of the TGN compartments decrease as they produce vesicles. After released from the Golgi, free TGN compartments continue to contract and they were seen to fragment into clusters of vesicles. The shrinkage of the plant TGN and its final disassembly suggest that the plant TGN is not a long-lasting organelle that is replenished regularly by membrane trafficking.