Chromatography-Driven Metabolomic Insights into Tomato Resistance Against Bacterial Wilt

Ralstonia solanacearum, the causal agent of bacterial wilt, severely disrupts the vascular function of tomato plants, which results in significant yield losses. A joint study conducted by researchers at the Science Campus University of South Africa and the University of Venda (Thohoyandou, South Africa) investigated the metabolomic shifts in tomato plants treated with garlic (Allium sativum) crude extract, Bacillus subtilis, and their combination, to assess their roles in enhancing resistance to R. solanacearum. Metabolomic profiling was conducted using ultra-high performance liquid chromatography coupled with quadruple time-of-flight mass spectrometry (UHPLC-QTOF-MS) to identify and quantify key metabolites associated with stress response. A paper based on this study was published in Plant-Environment Interactions (1).

A staple crop with significant economic and nutritional value, the tomato (Solanum lycopersicum L.) faces extensive challenges from the invasion of bacterial wilt, a harmful and damaging infection triggered by R. solanacearum (2,3), which infests the vascular tissue of the plant, bringing about rapid wilting, inhibition of growth, and eventual death, greatly impacting the yield of tomato crop worldwide (4,5). Chemical treatments and other traditional control methods for bacterial wilt often fall short because of the pathogen's persistence and adaptability (6). “As a result,” the researchers stated, “there is increasing interest in sustainable alternatives, such as biological control agents and plant-derived compounds. However, a deeper understanding of the biochemical mechanisms underlying tomato's response to R. solanacearum and biocontrol treatments is essential for optimizing these strategies.” (1)

Metabolomics provides a useful tool for addressing this gap by offering a systems level perspective on metabolic changes in response to biotic stress (7,8) Tools such as chromatography and spectrometry allow for the detection, cataloging, and comparison of thousands of metabolites, which provides insight into the basic biochemical and physiological responses of plants to invasion of pathogens and biocontrol treatments (9,10).

The researchers reported that their profiling showed that garlic extract upregulated (the increase of a response to a stimulus due to increase in the number of receptors on the cell surface [11]) key phenolic compounds, such chlorogenic acid and caffeoyl glucaric acid; these compounds contribute to pathogen defense by the reinforcement of cell structures and mitigation of oxidative stress. Chlorogenic acid accumulation was especially noticeable in garlic-treated plants, while caffeoyl glucaric acid displayed flexible regulation across the treatments. Flavonoid levels were generally downregulated (the reduction or suppression of a response to a stimulus due to a decrease in the number of receptors on the cell surface [12]), which the researchers said indicate a “metabolic shift favoring phenylpropanoid pathways in response to disease stress. “Furthermore,” they continued, “lipid-related metabolites, such as 12-dienoate, were reduced in the combined treatment, whereas Juniperoside III was up-regulated in B. subtilis-treated plants, suggesting selective regulation of saponin metabolism.” (1)

“These findings,” the authors wrote, “indicate that garlic extract enhances plant defense primarily through phenylpropanoid-mediated structural reinforcement, while B. subtilis contributes to disease suppression through microbial interactions rather than significant metabolic shifts. Understanding these metabolic trade-offs offers valuable insights into optimizing bacterial wilt management strategies, ultimately improving tomato resilience and productivity.” (1)

Additional research is needed to determine the optimal concentrations of garlic extract for enhanced metabolic responses and to clarify B. subtilis's mode of action are needed. In addition, they state that any future research should measure the synergistic possibilities of combining treatments under field conditions for the optimization of disease management strategies (1).

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References

1. Madlhophe, S.; Ogugua, U. V.; Makhubu, F. N. et al. Metabolomic Analysis of Tomato Plants Treated With Garlic Extract, Bacillus subtilis, and Their Combination for Defense Against Bacterial Wilt. Plant Environ. Interact. 2025, 6 (6), e70102. DOI: 10.1002/pei3.70102
2. Vats, S.; Bansal, R.; Rana, N. et al. Unexplored Nutritive Potential of Tomato to Combat Global Malnutrition. Crit. Rev. Food Sci Nutr. 2022, 62 (4), 1003-1034. DOI: 10.1080/10408398.2020.1832954
3. Phiri, T. M.; Bhattarai, G.; Chiwina, K. E. et al. An Evaluation of Bacterial Wilt (Ralstonia solanacearum) Resistance in a Set of Tomato Germplasm From the United States Department of Agriculture. Agronomy 2024, 14, 350. DOI: 10.3390/agronomy14020350
4. Kunwar, S., Hsu, Y. C.; Lu, S. F. et al. Characterization 3333 of Tomato (Solanum lycopersicum) Accessions for Resistance to Phylotype I and Phylotype II Strains of the Ralstonia solanacearum Species Complex Under High Temperatures. Plant Breeding 2020, 139: 389–401. DOI: 10.1111/pbr.12767
5. Oussou, G. F., Sikirou, R.; Afoha, S. A. et al. Resistance Assessment of Tomato (Solanum lycopersicum L.) and Gboma (Solanum macrocarpon L.) Cultivars Against Bacterial Wilt Caused by Ralstonia solanacearum in Benin. Pakistan Journal of Phytopathology 2020, 32, 241–249. DOI: 10.33866/phytopathol.030.02.0610
6. Nihorimbere, G.; Korangi Alleluya, V.; Nimbeshaho, F. et al. Bacillus-Based Biocontrol Beyond Chemical Control in Central Africa: The Challenge of Turning Myth into Reality. Front. Plant Sci. 2024, 15, 1349357. DOI: DOI: 10.3389/fpls.2024.1349357
7. Ghatak, A.; Chaturvedi, P.; Weckwerth, W. Metabolomics in Plant Stress Physiology; In Plant Genetics and Molecular Biology, 187–236. Springer, 2018.
8. Allwood, J. W.; Williams, A.; Uthe, H. et al. Unravelling Plant Responses to Stress-The Importance of Targeted and Untargeted Metabolomics. Metabolites 2021, 11 (8), 558. DOI: 10.3390/metabo11080558
9. Klassen, A., Faccio, A. T.; Canuto, G. A. B. et al. Metabolomics: Definitions and Significance in Systems BiologyIn Metabolomics: From Fundamentals to Clinical Applications, 3–17. Springer, 2017.
10. Wishart, D. S. Metabolomics for Investigating Physiological and Pathophysiological Processes. Physiol. Rev. 2019, 99 (4), 1819-1875. DOI: 10.1152/physrev.00035.2018
11. Upregulation. Mirriam-Webster website. https://www.merriam-webster.com/medical/upregulation (accessed 2025-12-12)
12. Downregulation. Mirriam-Webster website. https://www.merriam-webster.com/medical/downregulation (accessed 2025-12-12)