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Soil-borne diseases cause approximately 10-20% yield loss in tomato cultivation each year. Intensive cultivation and climate change are contributing to the rising incidence of these infections. Recent studies have shown that adjusting root-associated microbes can enhance crop resilience to environmental changes. Last year, we conducted a 16S rRNA metagenomic analysis of rhizosphere soil samples from popular market varieties of eggplant and tomato rootstocks, as well as disease-resistant and susceptible tomato varieties. This analysis revealed the abundance of operational taxonomic units (OTUs) and highlighted the similarities and differences among the samples. Based on these findings, this year we are focusing on investigating the bacterial populations with higher abundance differences, mainly Sphingobium and nitrogen-fixing bacteria, using selective media to enrich and isolate them. Additionally, purified bacterial isolates will be further tested for plant growth-promoting activities, such as nitrogen fixation, phosphorus solubilization, and ACC deaminase activity, as well as for their antagonistic capability against Ralstonia solanacearum. Ten strains were identified with significant plant growth-promoting potential. Antagonism assays against Ralstonia solanacearum revealed that 6 strains exhibited strong antagonistic activity. Further greenhouse trials demonstrated that 3 of these strains significantly enhanced resistance to bacterial wilt in tomato seedlings. Future work will focus on elucidating the antagonistic mechanisms of these promising strains and optimizing their culture conditions for field trials, with the aim of integrating them into tomato cultivation as effective biocontrol agents.
![]() ▲Figure. Antagonistic activity assay of soil-isolated strains against Ralstonia solanacearum |
![]() ▲Fig. Evaluation of soil-isolated strains for enhancing tomato resistance to bacterial wilt A: Isolated strains A ; B: Isolated strain C. From left to right: untreated control, R. solanacearum inoculation, isolated strain treatment, and isolated strain + R. solanacearum inoculation |