Local and Systemic Accumulation of Pathogenesis-Related Proteins in Tobacco Plants Infected with Tobacco Mosaic Virus. Thierry Heitz. Institute de Biologie Moleculaire des Plantes du CNRS, Universite Louis Pasteur, 12, rue du General Zimmer, 67084 Strasbourg Cedex, France. Bernard Fritig, and Michel Legrand. Institut de Biologie Moleculaire des Plantes du CNRS, Universite Louis Pasteur, 12, rue du General Zimmer, 67084 Strasbourg Cedex, France. MPMI 7:776-779. Accepted 3 August 1994. Copyright 1994 The American Phytopathological Society.

Tobacco mosaic virus-infected tobacco is a well-defined plant-pathogen system where a set of pathogenesis-related (PR) proteins have been isolated and characterized. We have used a series of seven antisera raised against purified proteins to study, by western blotting, the distribution of four families of PR proteins in leaves of tobacco mosaic virus-infected plants. The highest induction of all the PR proteins was found in a restricted number of cells surrounding the lesions. Differential patterns of accumulation of acidic and basic PR isoforms were detected further from the infection site where systemic acquired resistance is known to develop. Acidic PR proteins were barely detectable between the lesions and were present in variable amounts in upper uninoculated leaves. The basic isoforms, present at low levels in control leaves, were found to be significantly induced both between the ne-crotic spots on inoculated leaves and at distance in uninoculated parts of inoculated plants.