Abstract:[Background] Ralstonia solanacearum-induced tomato bacterial wilt is a major soil-borne disease in tomato cultivation, and effective control strategies remain limited. Screening antagonistic strains and developing biocontrol agents have become primary objectives in combating this disease. [Objective] To elucidate the growth-promoting effects, disease-preventing efficacy, and biocontrol mechanisms of Pseudomonas aeruginosa strain B-6 through laboratory and field trials and whole genome sequencing. [Methods] We employed the root irrigation method to evaluate the control efficacy of strain B-6 fermentation broth against tomato bacterial wilt, and then employed the seed soaking treatment to assess the growth-promoting effects of the strain on tomato seedlings. The second- and third-generation sequencing technologies were integrated to reveal the whole genome sequence of strain B-6. Gene functional annotation was performed via NR, Swiss-Prot, KEGG, COG, and GO databases. [Results] The results of laboratory and field experiments indicated that the control efficacy of the fermentation broth of strain B-6 decreased significantly as the dilution ratio increased. The 50-fold dilution group exhibited over 60% control effect against tomato bacterial wilt and could significantly promote the elongation of plumules and radicles. Genome sequencing showed that its total length was 6 456 367 bp, with the G+C content of 66.37%, containing 75 tRNA genes and 12 rRNA genes. Through combined annotation using multiple databases, 5 994 genes were successfully annotated. Among the 16 secondary metabolite synthesis gene clusters, 8 were completely matched with the synthesis gene clusters of known bacteriostatic compounds such as pyoluteorin, l-2-amino-4-methoxy-trans-3-butenoic acid, and pyocyanine, which suggested the molecular basis for its bacteriostatic activity. The coding region coding sequence (CDS) was predicted to be annotated to 5 865 genes, with 247 carbohydrate-active enzymes (CAZyme). [Conclusion] Strain B-6 demonstrates promising biocontrol activity against tomato bacterial wilt and promotes tomato growth. Its genome contains diverse antimicrobial metabolite biosynthetic gene clusters, which underscores the development potential of this strain as a high-efficacy biocontrol agent.
