Biocontrol of Southern Blight Caused by Sclerotium rolfsii in Pepper Plants Using Bacillus subtilis GJ6-14

Southern blight, caused by the soil-borne fungus Sclerotium rolfsii, is a serious disease that affects many economically important crops. In this study, we selected Bacillus subtilis GJ6-14, from a total of 260 strains, to control Southern blight in pepper plants. In both seedling and plant tests, GJ6-14 significantly suppressed disease incidence and severity compared to control, furthermore, GJ6-14 demonstrated efficient colonization in the rhizosphere by maintaining the population from log 5.41 to log 3.92 in the pathogen-inoculated plants, indicating its potential as a biocontrol agent. Molecular analysis revealed up-regulation of defense-related genes, such as a 7.6-fold increase in LOX1 and 15.5-fold increase in PR1, at 72 hr after inoculation of S. rolfsii in GJ6-14-treated plants, suggesting activation of plant defense mechanisms. Overall, our findings highlight the promising role of B. subtilis GJ6-14 as a potential biocontrol agent in sustainable management of Southern blight in pepper plants.