Cellular and Molecular Studies on Plasmodemata

这项研究将整合关于胞间连丝(PD)的生物物理、生化、细胞、生理和遗传学研究，以建立一个适当的框架，从而能够研究植物调节其细胞间通讯系统的细胞过程。生物物理研究将在一个简单的蜂窝系统上进行，以确定单位局部放电电导。这种测量对于进一步分析PD的亚结构以及为协调细胞对细胞大小排除限制的细胞控制的详细研究提供严格的基础是必不可少的。还将进行关于钯在溶质通量中的作用的生理学研究。由于帕金森病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，以识别控制继发性帕金森病形成的过程。在Beachy和加州大学戴维斯分校的William Lucas博士正在进行的这项合作中，已经确定了表达TMV 30 kDa运动蛋白(MP)的转基因烟草植株存在PD，其大小排除限制被上调到超过9.4 kDa。30 kDa TMV-MP影响这一变化的方式还有待进一步探讨。推测该蛋白与胞间连丝直接相互作用。基于这一概念，提出了PD蛋白的生化分离纯化方法。将在拟南芥中开发一个遗传系统，以鉴定和分离与病毒运动和PD功能有关的基因。胞间连丝是单个植物细胞之间的微小通道。通过这些通道传递分子的细胞间通讯对于整个植物的正常发育和生理功能是至关重要的。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。病毒编码的蛋白质有效地扩大了胞间连丝通道，促进了病毒通过胞间连丝的过程。这项研究将利用病毒蛋白来鉴定和研究植物胞间连丝的成分。对胞间连丝成分的了解将有助于进一步研究胞间连丝的形成和调节胞间连丝的分子运输机制。这一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.