Fig. 7: Effects of Ammoniphilus sp. on root metabolic profiles.

a Two-week-old tomato plants were transferred to hydroponic systems and exposed to −Fe (0 μM Fe) treatment with the presence of heat-killed (control) or living (+AS27) bacterial strains at a final concentration of 5 × 107 CFU mL⁻¹ for indicated times. Subsequently, root samples were harvested for LC-MS analysis. b, c Volcano plot depicting differential metabolites between the control and AS27-inoculated plants. d, e Venn diagram showing enriched and depleted metabolites that were shared between the control and AS27-inoculated plants. f LC–MS chromatograms displaying metabolites in bacterial culture of AS27. Additionally, two-week-old WT and NahG transgenic tomato plants were transferred to hydroponic systems and exposed to −Fe (0 μM Fe) treatment with and without the presence of heat-killed or living WT (AS27) and mutant (ΔglnA) bacterial strains at a final concentration of 5 × 107 CFU mL⁻¹, and/or with the presence of 3 μM SA, respectively. g Representative images of plant phenotypes were recorded after 12 days of growth. Furthermore, h SA levels, i PR1 expression, j bacterial colonization, and k CFU quantification were determined in the plants after 3 d of treatment. Different lowercase letters indicated significant differences among the different treatments using Duncan’s multiple range tests at p < 0.05 (n = 15 plants per group). Error bars indicate standard deviation of the mean.