Application of Endophytic Bacteria from Tomato Stems to Control Bacterial Wilt Disease in Tomato and Enhance Plant Growth

Bacterial green wilt (BGW) disease, caused by Ralstonia solanacearum bacterium, is a devastating bacterial disease of tomatoes occurring in tropical zones, resulting in substantial yield losses in production fields. Biological control agents (BCAs), particularly plant endophytes such as bacteria, are becoming increasingly popular in microbial technology for cropping systems. In this study, we assessed the potential of endophytic bacteria from tomato plants to suppress the BGW caused by R. solanacearum in tomato plants. The research study revealed that out of the 9 endophytic strains isolated, Bacillus amyloliquefaciens TO3 demonstrated a strong antagonistic ability towards R. solanacearum, with the zone of inhibition approximately 16.58 ±0.19 mm. This strain also produced cell wall-degrading enzymes (amylase, protease, and cellulase), and indole acetic acid (IAA). In addition, the greenhouse experiments showed that applying strain TO3 before the infection of R. solanacearum led to a high protective effect against the BGW and a significant increase in plant height compared to the non-inoculated ones. In field conditions, inoculating tomato seedlings with strain TO3 resulted in a disease reduction of over 55% against the BGW compared to the nontreated control. Moreover, treatment with strain TO3 increased the yield of tomato fruits by up to 47.93% compared to nontreated control plants. These findings indicate the potential use of B. amyloliquefaciens TO3 in preventing the BGW disease caused by R. solanacearum on tomato plants.