Curcumin triggers the immunity response in kiwifruit against Botrytis cinerea

•Curcumin induced a cell wall stress in Botrytis cinerea.•Curcumin promoted the production of chitin in cell walls of B. cinerea.•B. cinerea treated by curcumin enhanced immune response in kiwifruit during infection. Curcumin has been reported to exhibit anti-microbial activity; however, an understanding of its effects on the phytopathogens is limited. In the present study, the effect of curcumin on gray mold (Botrytis cinerea) infection of kiwifruit was evaluated. Results showed that the exposure of B. cinerea to curcumin promoted an increase in the total and surface-exposed chitin in the cell walls of the pathogen. The mycelia of B. cinerea treated with curcumin also exhibited a higher sensitivity to cell-wall-perturbing agents. The infection of curcumin-treated kiwifruit by B. cinerea elicited higher levels of H2O2 production, callose deposition, and the expression of CERK1 and several defense-related genes relative to untreated fruit, leading to a lower fungal biomass and decreased disease development in inoculated kiwifruit. These results suggest that curcumin promotes the production of chitin in cell walls of B. cinerea to provide protection from cell wall stress. The presence of a higher level of chitin molecules on the cell surface of B. cinerea induces a stronger immune response in kiwifruit than observed by B. cinerea hyphae without exposure of curcumin.