Abstract
Large quantity of secretory proteins and extracellular glycans are transported to plasma membrane during cell growth. Secretory vesicles generated at the trans-Golgi network (TGN) are known to carry these materials. Here we report an undescribed mobile unit, which we term secretory vesicle cluster (SVC), in post-TGN secretory pathway in plant cells. Electron microscopy of quick-frozen cells, four-dimensional analysis of tobacco culture BY-2 cells expressing fluorescent-tagged secretory carrier membrane protein 2 (SCAMP2) and other analyses indicated that SVC is generated from TGN, moves in the cell and eventually fuses with the plasma membrane. SVC also fuses to cell plate in dividing plant cells. Moreover, SVC are observed in rice and Arabidopsis cells. Thus, the SVC is a mobile structure involved in mass transport from TGN to the cell exterior in plants. We will report about distribution of SVC in plant tissue.
