Pathogenesis - Related Proteins of Nicotiana

本研究将详细研究烟草花叶病毒感染诱导烟草植物合成的致病相关蛋白PR1组的调控。初步研究表明，PR1转录本水平在感染后升高。拟议的研究将通过测量个体转录率和mRNA稳定性来调查增加的原因，并将确定翻译调节是否也发生。如果合适，PR1基因的调控元件将被识别。PR1蛋白的命运也将被研究。初步证据表明，蛋白质是分泌的；蛋白质的分泌途径和最终的细胞外定位（如果有的话）将使用遗传学和细胞学技术的结合来检查。最后，为了鉴定PR1蛋白的功能，将构建组成性过表达PR1蛋白的转基因植物。人们早就知道，真菌、病毒或细菌对维管植物的感染通常会导致所谓的超敏反应。除了附近组织的死亡有助于限制感染因子的传播外，这种反应经常导致整个植物对病原体产生抗性（“获得性抗性”）。耐药性并不局限于最初的传染因子；因此，例如，细菌感染可以导致对病毒感染的抗性。此外，某些化学物质也会引起这种反应。最近，研究表明，这种反应伴随着一些小蛋白质的合成，这些小蛋白质在耐药性中的作用尚不清楚。拟议的研究将阐明调控一组此类致病相关蛋白合成的遗传机制，并确定这些蛋白在细胞分泌后的最终命运。该研究将对我们对植物基因调控和病害过程的认识有重要的推动作用。

The proposed research will examine in detail the regulation of the PR1 set of the Pathogenesis-Related (PR) proteins whose synthesis in tobacco plants is induced by infection with Tobacco Mosaic Virus. Preliminary work indicates that the level of PR1 transcripts increases after infection. The proposed research will investigate the cause of the increase by measuring individual transcription rates and mRNA stabilities, and will determine if translational regulation also occurs. If appropriate, regulatory elements of the PR1 genes will be identified. The fate of the PR1 proteins will also be examined. Preliminary evidence indicates that the proteins are secreted; the secretory pathway and eventual extra-cellular localization (if any) of the proteins will be examined using a combination of genetic and cytological techniques. Finally, transgenic plants that constituitively over-express PR1 proteins will be constructed in an effort to identify the function(s) of the PR1 proteins. It has long been known that infection of vascular plants by fungi, viruses or bacteria often leads to a so-called hypersensitive response. Besides the death of nearby tissue, which helps limit the spread of the infectious agent, the response frequently leads to establishment of resistance to the pathogen ("acquired resistance") throughout the plant. Resistance is not limited to the original infectious agent; thus, for example, a bacterial infection can lead to resistance to viral infection. Furthermore, certain chemicals can also elicit the response. More recently, it has been shown that the response is accompanied by the synthesis of a number of small proteins whose role in resistance is still unclear. The proposed research will clarify the genetic mechanisms that regulate synthesis of one set of such Pathogenesis-Related proteins and, as well, identify the eventual fate of the proteins following their secretion by the cell. The research should advance significantly our understanding of gene regulation and of the disease process in plants.