ACCUMULATION OF PATHOGENESIS-RELATED PROTEINS IN THE EPIDERMIS OF TOMATO LEAVES INFECTED BY CLADOSPORIUM-FULVUM

Upon infection by Cladosporium fulvum, tomato plants start to produce pathogenesis-related (PR) proteins. The PR proteins 1,3-beta-glucanase, chitinase, and PR-lb accumulated near the stomata in the lower epidermis of C fulvum-inoculated tomato leaves as could be determined by immunolocalization with polyclonal antibodies. However, no differences in accumulation of PR proteins between a compatible and an incompatible interaction were found. Results obtained from enzyme activity measurements of 1,3-beta-glucanase and chitinase on similar leaf material as used for the immunolocalization did not fully reflect the immunolocalization data. The antibodies possibly detect only the extracellular but not the intracellular enzymes. The accumulation of PR proteins near the stomata might be part of a general defence response of plants against pathogens and potential pathogens.