Pathogenesis - Related Proteins of Nicotiana

点击翻译按钮获取中文摘要

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.