Evidence for Transcriptional Regulation of Beta-1,3-Glucanase as it Relates to Induced Systemic Resistance of Tobacco to Blue Mold. M. Lusso. Department of Plant Pathology, University of Kentucky, Lexington, KY, 40546, U.S.A. J. Kuc. Department of Plant Pathology, University of Kentucky, Lexington, KY, 40546, U.S.A. MPMI 8: 473-475. Accepted 3 January 1994. Copyright 1995 The American Phytopathological Society.

The hybridization signal for Beta-l,3-glucanase (PR-N) mRNA was detected in the lower inoculated leaves and upper uninfected leaves of N-gene tobacco plants 3 and 12 days, respectively, after inoculation of lower leaves with tobacco mosaic virus (TMV). The signal markedly increased 1 to 2 days after challenge of upper leaves with Peronospora tabacina, whereas only a slight increase was apparent 3 to 4 days after mock challenge. The signal was not apparent in mock challenged upper leaves, but it was detected 4 days after challenge in upper leaves of plants mock inoculated with TMV. Plants inoculated with TMV were highly protected against P. tabacina. These results indicate a positive association of PR-N mRNA with induced resistance to P. tabacina and the apparent scnsitiza-tion of the induced plants to rapidly produce PR-N mRNA after challenge with P. tabacina.