Leaf Aqueous Extract Differentially Inhibits the Growth of Three Bacterial Tomato Pathogens.

As available tools for crop disease management are scarce, new, effective, and eco-friendly solutions are needed. So, this study aimed at assessing the antibacterial activity of a dried leaf Labill. aqueous extract (DLE) against pv. (), (), and (). For this, the inhibitory activity of different concentrations of DLE (0, 15, 30, 45, 60, 75, 90, 105, 120, 135, and 250 g L) was monitored against the type strains of , , and through the obtention of their growth curves. After 48 h, results showed that the pathogen growth was strongly inhibited by DLE, with the most susceptible species (15 g L MIC and IC), followed by (30 g L MIC and IC), and (45 and 35 g L MIC and IC, respectively). Additionally, using the resazurin assay, it was possible to verify that DLE considerably impaired cell viability by more than 86%, 85%, and 69% after , , and were incubated with DLE concentrations equal to or higher than their MIC, respectively. However, only the treatment with DLE at 120 g L did not induce any hypersensitive response in all pathogens when treated bacterial suspensions were infiltrated onto tobacco leaves. Overall, DLE can represent a great strategy for the prophylactic treatment of tomato-associated bacterial diseases or reduce the application of environmentally toxic approaches.