Unveiling the efficacy of a bacterial antagonist in the management of tomato wilt disease caused by Ralstonia solanacearum

Abstract

The long-term application of agrochemicals, including pesticides, in intensive agricultural practices to protect crops from biotic stresses results in the emergence of resistance among phytopathogens and the ineffectiveness of chemical applications. The microbiological strategies, in contrast, minimize the reliance on chemicals and, hence, reduce environmental and human health risks. Bacterial wilt of tomato induced by Ralstonia solanacearum is one of the most destructive diseases worldwide that requires urgent attention to develop a safer and more efficient method to control the phytopathogen. The present work was conducted in the year 2022-2023. In this study, the bacterial wilt was managed by an antagonist bacterium, Pseudomonas fluorescens, exhibiting variable morphological, biochemical, and plant growth-promoting activities. The P. fluorescens inhibited the growth of R. solanacearum in plate assay at different time intervals (0-48 h). The SEM image of R. solanacearum cells cultured with P. fluorescens revealed pores, distortion, and fragmented cell envelope, while the untreated bacterial cells were uniform and smooth. Tomato plants infected with R. solanacearum showed 89% disease incidence compared to uninfected but PGPR-inoculated tomato plants. Application of P. fluorescens reduced disease incidence by 63% compared to R. solanacearum infested plants. Furthermore, plant length enhanced by 21 and 26% significantly following bacterial inoculation after three and four weeks of growth. Conclusively, this study emphasizes the effectiveness of using PGPR as a potent strategy for managing wilt disease in vegetable crops, especially tomato.