A Distinct Pathway for Polar Exocytosis in Plant Cell Wall Formation.

Hao Wang, Xiaohong Zhuang, Xiangfeng Wang, Angus Ho Yin Law, Teng Zhao, Shengwang Du, Michael M T Loy, Liwen Jiang

Plant physiology 2016 Oct

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Post-Golgi protein sorting and trafficking to the plasma membrane (PM) is generally believed to occur via the trans-Golgi network (TGN). In this study using Nicotiana tabacum pectin methylesterase (NtPPME1) as a marker, we have identified a TGN-independent polar exocytosis pathway that mediates cell wall formation during cell expansion and cytokinesis. Confocal immunofluorescence and immunogold electron microscopy studies demonstrated that Golgi-derived secretory vesicles (GDSVs) labeled by NtPPME1-GFP are distinct from those organelles belonging to the conventional post-Golgi exocytosis pathway. In addition, pharmaceutical treatments, superresolution imaging, and dynamic studies suggest that NtPPME1 follows a polar exocytic process from Golgi-GDSV-PM/cell plate (CP), which is distinct from the conventional Golgi-TGN-PM/CP secretion pathway. Further studies show that ROP1 regulates this specific polar exocytic pathway. Taken together, we have demonstrated an alternative TGN-independent Golgi-to-PM polar exocytic route, which mediates secretion of NtPPME1 for cell wall formation during cell expansion and cytokinesis and is ROP1-dependent. © 2016 American Society of Plant Biologists. All Rights Reserved.

Citation

Hao Wang, Xiaohong Zhuang, Xiangfeng Wang, Angus Ho Yin Law, Teng Zhao, Shengwang Du, Michael M T Loy, Liwen Jiang. A Distinct Pathway for Polar Exocytosis in Plant Cell Wall Formation. Plant physiology. 2016 Oct;172(2):1003-1018