Induction of PR1 Protein Synthesis in Nicotiana

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As a model to study how plants react to pathogenic attack the response of tobacco (Nicotiana tabacum) to tobacco mosaic virus (TMV) is being investigated. In response to a variety of pathogenic and chemcial agents tobacco plants produce large amounts of pathogenesis-related (PR) proteins whose synthesis has been associated with resistance to TMV. This laboratory has focused on the synthesis, location, and function of the PR1 family of these proteins. Salicylic acid (SA) has been used extensively as an inducer of PR proteins and local acquired resistance to TMV. These observations together with the recent finding that endogenous SA levels rose at least 20-fold in leaves of TMV-resistant, but not susceptible, tobacco after TMV inoculation suggest that SA may be part of the natural induction pathway following TMV infection. A major objective is to determine the role of SA in induction of PR1 genes. This may provide an important avenue to define intermediate steps in the signal transduction pathway that leads to the defense response following pathogenic assault. As part of this analysis the cis acting element(s) and trans acting factor(s) necessary for SA induction will be defined. Many plants respond to viral infection by the production of certain proteins which have been termed "pathogenesis-related proteins". The goal of this research is to understand the molecular signals by which the genes for pathogenesis-related protein are activated. The results of this research will contribute to basic knowledge of the mechanisms of plant defense against viruses.