Comparative metabolomic profiling of resistant and susceptible tomato cultivars against Ralstonia solanacearum revealing key pathways and metabolites of defense response

Tomato is a globally important crop and model for plant-pathogen studies, with bacterial wilt caused by Ralstonia solanacearum posing a major threat. Understanding metabolic changes in resistant and susceptible cultivars during infection is vital. This study investigated the metabolic responses of resistant (Hawaii 7996) and susceptible (Marmande) tomato cultivars under R. solanacearum infection, identified key metabolites and defense pathways, and compared metabolite accumulation using high-resolution mass spectrometry. Liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS) was used to analyze root samples at 6 days post-inoculation. Data processed in MetaboAnalyst 6.0 identified differentially accumulated metabolites through multivariate analysis, heatmaps, and volcano plots. Pathway and chemical superclass enrichment analyses revealed distinct responses between cultivars. The resistant cultivar showed markedly higher abundance of defense-related metabolites in pathways such as glutathione metabolism, tropane/piperidine/pyridine alkaloid biosynthesis, phenylalanine metabolism, terpenoid backbone biosynthesis, and sesquiterpenoid/triterpenoid biosynthesis, indicating a robust defense response. In contrast, the susceptible cultivar exhibited fewer changes in these pathways, suggesting a weaker defense. Baseline differences were also observed, with the resistant cultivar displaying elevated levels of certain defense-associated metabolites even without infection. Overall, the findings clearly demonstrate that resistance in Hawaii 7996 is driven by a strong activation and maintenance of key defense-related metabolic pathways, whereas Marmande fails to initiate comparable metabolic reprogramming under infection. These results provide direct metabolomic evidence linked to bacterial wilt resistance and identify specific metabolites and pathways that may serve as promising biochemical targets for breeding disease-resilient tomato cultivars.