植物病毒成功侵染的最首要和重要步骤是运动蛋白介导病毒穿过胞间连丝的胞间运动，相关的研究主要来自30K移动蛋白家族，而分子量较小的移动蛋白介导病毒的胞间运动功能及其机理尚不明确。申请者前期通过sRNA高通量检测，发现我国一种新发病毒芜菁黄化病毒侵染辣椒，探明该病毒侵染辣椒的机制，对于明确该病毒的潜在威胁具有重要科学意义。本项目结合移动蛋白介导植物病毒通过胞间连丝的胞间运动前沿研究进展，通过分子生物学、细胞生物学及生物化学等多学科手段，开展芜菁黄化病毒P4蛋白介导该病毒胞间运动的功能、P4蛋白关键结构域及功能等研究，系统的揭示芜菁黄化病毒编码的介导病毒胞间运动的P4蛋白功能。本项目的实施将有助于认识正单链RNA病毒编码的小分子量移动蛋白的功能，也将有助于构建小分子量移动蛋白介导病毒胞间运动的理论模型。

Current reports for cell-to-cell movement of plant viruses via plasmodesmata mediated by movement protein encoded by plant viruses are most coming from movement proteins from 30 K family, little of that from movement proteins with smaller molecular weight. Our preliminary studies show that movement protein P4 encoded by Turnip yellows virus has highly conserved domains with movement protein of 30 K family. Based on those findings, combined with recent progress on the cell-to-cell movement via plasmodesmata mediated by movement proteins, this project intends to use the integrated approaches of molecular biology, cell biology and biochemistry to reveal the capacity of cell-to-cell movement mediated by P4 protein, functions of conserved domains of P4 protein, to understand the mechanism of cell-to-cell movement via plasmodesmata mediated by movement protein P4 of Turnip yellows virus. The scientific significance of this project will not only help to understand the mechanisms of cell-to-cell movement mediated by smaller molecular weight movement proteins of positive single strand RNA viruses, and also help to construct the theoretical model of cell-to-cell movement of viruses via plasmodesmata mediated by smaller molecular weight movement proteins.