Abstract Objective Soil-borne plant pathogens are a significant cause of economic loss in global agriculture. In a previous study, fermented botanical product (FBP) treatment was shown to suppress bacterial wilt disease caused by Ralstonia pseudosolanacearum ( Rps ) in tomatoes. This study evaluated whether treatment with FBP suppresses soil‑borne bacterial pathogens and induces host plant defense responses. Results Seedlings of three Solanaceae species and nine families of plants treated with water or FBP for 48 h were inoculated with Rps and wilting symptoms were compared 14 days post inoculation. FBP treated plants showed an increase in the number of individuals without wilting symptoms and a decrease in the number of dead individuals. In addition, inoculation with C. michiganensis subsp. michiganensis , which belongs to the same soil-borne bacterial disease group, showed similar suppression in tomatoes treated with FBP. To further confirm the root defense response to FBP treatment, we analyzed the amount of lignin, which is known to be a physical barrier against pathogens, and found that FBP application increased the amount of lignin in Solanaceae plants. These results suggest that FBP suppress soil-borne bacterial diseases by supporting lignin development.
Mizuno et al. (Tue,) studied this question.