反式高尔基网状体是细胞内蛋白质分选、包装和运输的主要核心细胞器，在经典蛋白质运输途径中发挥着重要的生物学功能。我们前期研究表明，植物细胞内存在一条非典型蛋白质胞吐外泌途径。它不经过反式高尔基网状体，直接由高尔基体介导细胞壁合成与刚性关键果胶甲酯酶的极性胞吐外泌，来调控细胞极性的产生和维系。但是，该非典型蛋白质胞吐外泌途径的生物发生规律，以及介导和调控它的分子作用机制都尚未被揭示。本项目拟采用最新的线性贝塞尔光片显微成像系统，通过五维高分辨影像技术揭示该非典型蛋白质胞吐外泌途径的生物发生和作用规律。同时，进一步结合基因编辑和突变、细胞器蛋白质组学和遗传突变等手段，探明介导与调控该非典型途径的受体蛋白和调控因子，阐明其在植物细胞极性产生和维系中的分子作用机制。本项目对高尔基体介导的蛋白质分泌网络调控细胞极性和细胞壁合成研究有重要理论价值。

Trans-Golgi network, a key organelle in protein sorting, packaging and transportation, plays essential roles in the conventional protein trafficking pathways. Our previous studies showed that there is a distinct unconventional protein exocytosis pathway which mediates the secretion of pectin methylesterase bypassing TGN in plants. Pectin methylesterase is a vital enzyme that participates in regulating the plant cell wall formation and rigidity. Nevertheless, a key unanswered question is what is the underlying regulation mechanism of the unconventional protein exocytic pathway during polar cell growth and cytokinesis. In this study, we will employ the newly developed Line Bessel Sheet light-sheet microscope and advanced image processing and analysis software to reveal the spatiotemporal biogenesis of the unconventional protein polar secretion in plant cells. In addition, we will use a combination of gene editing and mutation, organelle proteomic and genetic approaches to characterize the regulatory proteins and interacting receptors which mediate the unconventional protein polar exocytosis to better understanding it molecular working mechanisms in regulating the polarity of plant cells. Our studies will advance our current understandings of Golgi related protein secretion network in regulating cell polarity in plants.