Suppression of the activity of non-specific elicitor from Cladosporium fulvum by intercellular fluids from tomato leaves

Abstract

Intercellular fluids from Cladosporium fulvum-infected tomato suppressed the induction of necrosis and the deposition of callose when co-injected into tomato leaflets with non-specific elicitors from culture filtrates and cell walls of C. fulvum. Similar suppressing activity was also detected in some, but not all, intercellular fluid preparations from uninoculated tomato indicating that the suppressing factor is probably of host origin. Heat lability of suppressor activity distinguished it from the specific elicitors which have been previously described in these intercellular fluids. Suppression of non-specific elicitor activity showed no race/cultivar specificity and appeared to be an enzymatic interaction between components of the intercellular fluids and the elicitor. Activity of both crude and purified preparations of the glycoprotein elicitor was suppressed. Differences in necrosis but not electrolyte leakage were observed between leaf discs injected with non-specific elicitor and intercellular fluids containing or lacking suppressor activity. Intercellular fluids from rust-infected bean also suppressed elicitor-induced necrosis. The ability of intercellular fluids to suppress activity of the non-specific elicitor suggests that this and similar elicitors may not exist for long in vivo.