植物的叶绿体含有约3000多种蛋白，其中90%以上的蛋白是由核基因组编码，这类蛋白在细胞质内合成后运输到叶绿体内部，对叶绿体的发育和功能起着重要作用。在这一运输过程中，核编码叶绿体蛋白如何在胞质内运输到叶绿体附近的研究较少，本项目采用RNAi方法获得水稻COPI亚基β'-COP表达下调的稳定突变体，研究COPI介导核编码叶绿体蛋白在胞质内运输的过程。首先通过蛋白iTRAQ分析，鉴定在Osβ'-cop RNAi突变体中差异表达的蛋白，利用pathway分析确定差异表达蛋白参与的最主要生化代谢途径和信号转导途径；其次在蛋白质组学分析结果的基础上，以代表3种胞内运输途径的蛋白（RuBisCO小亚基、α-淀粉酶和RuBisCO活化酶）为研究对象，采用原生质体瞬时表达、免疫共沉淀、激光共聚焦扫描分析等方法，研究COPI小泡参与核编码叶绿体蛋白运输的过程，揭示COPI在叶绿体发育与功能维持方面的作用。

In plants, more than 90% of 3000 chloroplast proteins are encoded by nuclear genome, synthesized in the cytosol and subsequently imported into the chloroplast. The protein targeting into chloroplast is an essential cellular event for maintaining chloroplast function and plant life. But the question is, at present, few researches for how the proteins targeting to chloroplast's surface within the cytosol. To further explore the role of COPI-mediated the cytoplasmic transport of nuclear-encoded chloroplast protein, we utilized a strategy of RNA inference-mediated depletion of the β'-COP subunit of COP I. First, through the protein analysis of isobaric tags for relative and absolute quantitation (iTRAQ), differential expressed proteins of β'-cop-depleted plants were selected, and identified their biochemical pathways and signal transduction pathways by pathway analysis. Second, based on the proteomics result, we chose the proteins representing three general pathways of cytoplasmic transport for our study, such as Ribulose bisphosphate carboxylase/oxygenase small subunit (RbcS), α-amylase I and Ribulose bisphosphate carboxylase/oxygenase activase (RbcA). we showed that the COP I is participated in transport of nuclear-encoded chloroplast proteins directly according to the protoplast instantaneous expression, coimmunoprecipitation and laser confocal scanning microscope (LCSM) analysis. Together, our results demonstrated that COPI mediated the cytoplasmic transport of nuclear-encoded chloroplast protein, and maintaining chloroplast function.