Grey mould, caused by Botrytis cinerea, is a major fungal disease of tomato (Solanum
lycopersicum) world-wide. The aim of this study was to explore the molecular pathways involved
in the induced resistance against B. cinerea in tomato plants grown on biochar amended medium.
We observed that similar pathways of induction of defence-related gene expression take place in
leaves of plants grown in biochar-amended medium independently of the biochar type and that
the effect of biochar on gene expression increases with incubation time. In addition, a mutant
def1, deficient in jasmonic acid lost its induced resistance ability when grown in a greenhouse
biochar amended soil. This correlated with a loss of induction of expression of the genes
belonging to the salicylic and jasmonic acid pathways. We conclude that Induced resistance by
biochar amendment in tomato against grey mould depends on jasmonic acid synthesis.