Temporal and Spatial Expression of Chitinases and 1,3-ß-Glucanases in the Cladosporium Fulvum/Tomato Interaction

Abstract

Immunolocalization and in situ hybridization analysis of chitinases and 1,3-ß- glucanases were performed on tomato leaves infected by the fungus Cladosporium fulvum, the causal agent of tomato leaf mould. It was found that different pathogenesis related (PR) proteins accumulated in the intercellular space of infected tomato leaves, whereby the accumulation occurred two to four days earlier in an incompatible interaction than in a compatible interaction. In our studies antibodies were used which do not discriminate between intracellular (basic) and extracellular (acidic) isoforms of the enzymes. Peeled epidermal strips of infected tomato leaves showed chitinases and 1,3-ß-glucanases accumulating at or near stomata. Since stomata are natural sites of penetration for many plant pathogens, the accumulation of chitinases and 1,3-ß-glucanases at these sites might play an important role in the defense of plants against pathogens. However, with the tomato - C. fulvum interaction, no difference in accumulation near the stomata was found between compatible and incompatible interactions. Biochemical data revealed that the chitinase and 1,3-ß-gl]ucanase activity in the peeled lower epidermis was about the same as in the remaining of the infected leaf.