Induced resistance to B otrytis cinerea in C apsicum annuum by a F usarium crude elicitor fraction, free of proteins

Fusarium oxysporum f. sp. lycopersici ( FOL ) induces resistance in pepper against the airborne pathogen B otrytis cinerea and the soil‐borne pathogen V erticillium dahliae . However, its practical use is limited due to its pathogenicity to other crops. In this study we tested several fractions of a heat‐sterilised crude FOL ‐elicitor preparation to protect pepper against B . cinerea and V . dahliae . Only the protein‐free insoluble fraction of the preparation reduced B . cinerea infection. However, none of the fractions reduce V . dahliae symptoms. The insoluble protein‐free fraction induced expression of defence genes in the plant, namely a chitinase ( CACHI 2 ), a peroxidase ( CAPO 1 ), a sesquiterpene cyclase ( CASC 1 ) and a basic PR 1 ( CABPR 1 ). Even though the CASC 1 gene was not induced directly after treatment with the insoluble fraction in the leaves, it was induced after B . cinerea inoculation, showing a priming effect. The insoluble protein‐free FOL ‐elicitor protected pepper against the airborne pathogen through a mechanism that involves induced responses in the plant, but different to the living FOL .