Suppression of Phytophthora capsici infection and promotion of tomato growth by soil bacteria

Phytophthora capsici causes root, crown and fruit rot on many plant species including tomato and other solanaceous species. Plant growth promotion and suppression of P. capsici on tomato were assessed for three soil bacterial isolates, namely Bacillus amyloliquefaciens (UQ154), Bacillus velezensis (UQ156) and Acinetobacter sp. (UQ202). Cultures were applied as seed treatments (pre and post-infection inoculation) plus a soil drench at transplanting. The bacterial isolates significantly promoted growth of seedlings, as measured by root length, total fresh weight, and seedling vigor. We observed a reduction in pathogen load in tomato roots in both treatments using quantitative Polymerase Chain Reaction (qPCR). This work confirms the broad-spectrum activity of these bacterial isolates for our previous findings of biocontrol activity on different plants.