Cellular and Molecular Studies on Plasmodemata

这项研究将整合对胞间连丝（pd）的生物物理、生化、细胞、生理和遗传研究，建立一个适当的框架，然后允许对植物调节其细胞间通信系统的细胞过程进行调查。生物物理研究将在一个简单的细胞系统上进行，以确定单一的pd电导。这些测量对于pd的进一步子结构分析至关重要，并为细胞控制的详细研究提供了严格的基础，这些控制协调了细胞间的大小排斥限制。还将进行pd在溶质通量中的作用的生理学研究。由于pd可能是器官发育的重要决定因素，因此将建立一个实验系统，以确定控制继发性pd形成的过程。在这项正在进行的合作（Beachy和加州大学戴维斯分校的William Lucas博士）中，已经确定表达TMV的30 kDa运动蛋白（MP）的转基因烟草植物具有pd，其大小排除限制上调至超过9.4 kDa。30kda TMV-MP影响这种变化的模式将进一步探讨。据推测，这种蛋白直接与胞浆连丝体相互作用。基于这一概念，提出了pd蛋白的生化分离纯化方法。拟南芥的遗传系统将被开发，以允许鉴定和分离涉及病毒运动和pd功能的基因。间连丝是植物细胞间的微小通道。分子通过这些通道进行细胞间通讯对整个植物的正常发育和生理功能至关重要。在某些植物病毒感染中，病毒在局部位置进入细胞内部，并通过整个植物的胞间连丝从一个细胞传播到另一个细胞。病毒通过胞间连丝的通道是由一种病毒编码的蛋白质促进的，该蛋白质有效地扩大了胞间连丝通道。本研究将利用病毒蛋白对植物间连丝的组成成分进行鉴定和研究。了解胞间连丝的组成成分将有助于进一步研究胞间连丝的形成以及调控胞间连丝分子交通的机制。本研究结果将对植物细胞间通讯的基础知识做出重要贡献。

This research will integrate biophysical, biochemical, cellular, physiological and genetic studies on plasmodesmata (pd) to establish an appropriate framework that will then allow an investigation of the cellular processes by which the plant regulates its cell-to-cell communication system. Biophysical studies will be performed on a simple cellular system in order to determine the unitary pd conductance. Such measurements are essential for a further sub-structural analysis of the pd, as well as to provide a rigorous foundation for detailed studies on the cellular controls that orchestrate cell-to-cell size exclusion limits. Physiological studies on the role of pd in solute fluxes will also be performed. Since pd are likely to be an important determinant of organ development, an experimental system will be established that will permit identification of the processes that control secondary pd formation. In this ongoing collaboration (between Beachy and Dr. William Lucas of the University of California, Davis), it has been established that transgenic tobacco plants in which the 30 kDa movement protein (MP) of TMV is expressed have pd whose size exclusion limits are up-regulated to sizes in excess of 9.4 kDa. The mode by which the 30 kDa TMV-MP effects this change will be further explored. It is hypothesized that this protein interacts directly with the plasmodesma. Based on this concept, biochemical isolation and purification of pd proteins are proposed. A genetic system in Arabidopsis will be developed to permit the identification and isolation of genes involved in virus movement and pd function. %%% Plasmodesmata are microscopic channels between individual plant cells. Intercellular communication by passage of molecules through these channels is critical for the normal development and physiological function of the entire plant. In certain plant viral infections, the virus gains access to the cell interior at a localized site and passes from cell to cell through the plasmodesmata throughout the plant. Passage of the virus through plasmodesmata is facilitated by a virally encoded protein which effectively enlarges the plasmodesmatal channel. This research will take advantage of the viral protein to identify and study the components of the plant plasmodesmata. Knowledge of the components of plasmodesmata will facilitate further studies of the formation of plasmodesmata and the mechanisms by which molecular traffic through the plasmodesmata is regulated. The results of this research will be important contributions to basic knowledge of cell to cell communication in plants.