Profiling Pathogen-Induced Stress in Ginger Using Chromatographic Techniques

While ginger is an economically significant crop, its production is severely affected by fungal pathogens, especially Pythium aphanidermatum, which causes yield losses and decline in crop quality. Researchers at Mohanlal Sukhadia University (Udaipur, Rajasthan, India) and the Central University of Punjab (Bathinda, India) aimed to identify the fungal pathogens associated with ginger rhizome rot through molecular characterization for the evaluation of impact on plant physiological and biochemical responses. Antioxidant and phenolic metabolism enzyme activities were measured, with mycotoxin profiling conducted using column chromatography, thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). A paper based on this research was published in Frontiers in Microbiology (1).

A widely grown medicinal and culinary crop valued for its aromatic rhizomes, which contain bioactive compounds with notable antimicrobial, anti-inflammatory, and antioxidant properties (2), the cultivation of ginger (Zingiber officinale), despite its economic and therapeutic importance, is severely affected by soil-borne pathogens, particularly oomycetes like Pythium aphanidermatum, which cause soft rot disease. In addition, there are other oomycetes such as Pythium myriotylum which have also been identified as causal agents of soft rot in ginger, especially in China and Southeast Asia. P. myriotylum has been confirmed in recent molecular studies as one of the more commonly identified pathogens in investigations concerning soft-rot-infected ginger rhizomes (3). These findings emphasize the need for increased approaches in the management of this pathogen group, as the accurate identification of the causative pathogen is crucial in the achievement of successful cultivation (4).

In this study, ginger samples showing rot, discoloration, and wilting symptoms were collected from multiple agricultural fields in Udaipur, as well nearby areas such as Jhadol, Gogunda, and Badgaon, from farms that indicated a history of fungal infections. Samples were taken from plants at different growth stages and from different soil types to ensure a diverse collection (1).

From the results, the researchers were able to confirm the presence of P. aphanidermatum, which caused severe oxidative stress in ginger plants, including an increase in reactive oxygen species (ROS) accumulation, lipid peroxidation, and chlorophyll degradation. Purification and separation of toxic compounds from the crude extract of P. aphanidermatum collected from the samples were carried out using column chromatography, and fungal secondary metabolites were analyzed using TLC and GC–MS (1).

In addition, antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR) were upregulated significantly, as were phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO). Mycotoxin profiling uncovered secondary metabolites which contributed to fungal pathogenicity. The application of fungal crude extracts (F1-F3), 24 h prior to inoculation, reduced oxidative damage significantly, se well as preserved the physiological integrity of the plant, with F1 showing the most effective mitigation (1).

The researchers report that P. aphanidermatum infection inflicts severe oxidative stress and physiological damage in ginger, which was confirmed by the elevated ROS, malondialdehyde (MDA), and disrupted chlorophyll composition. The pre-emptive application of fungal crude extracts alleviated these effects, thus highlighting their possible role in plant defense. The findings provide additional insights into the pathogenic mechanisms of P. aphanidermatum as well as the phytotoxicity of its metabolites, which lays the foundation for future studies on detailed chemical characterization and field validation. Future studies, should concentrate on complete and specific metabolite profiling using nuclear magnetic resonance (NMR)-LC–MS, bioassay-guided purification, and the validation of findings under natural environmental setups, the researchers wrote(1).

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References

1. Meena, M.; Yadav, G.; Sonigra, P. et al. Molecular Identification and Pathogenic Impact of Pythium aphanidermatum on Ginger (Zingiber officinale): Insights into Oxidative Stress, Antioxidant Responses, and Mycotoxin Profiling. Front. Microbiol. 2025, 16, 1626700. DOI: 10.3389/fmicb.2025.1626700
2. Zhukovets, T.; Özcan, M. M. A Review: Composition, Use and Bioactive Properties of Gnger (Zingiber officinale L.) Rhizoms. J. Agroaliment. Proc. Technol, 2020, 26, 216. https://journal-of-agroalimentary.ro/admin/articole/47051L31_Tatiana_Zhukovets_2020_26(3)_200-2016.pdf
3. Lv, Y.; Li, Y.; Liu, X. et al. Identification of Ginger (Zingiber officinale Roscoe) Reference Genes for Gene Expression Analysis. Front Genet. 2020, 11, 586098. DOI: 10.3389/fgene.2020.586098
4. Archana, T. S.; Mesta, R. K.; Basavarajappa, M. P et al. Unravelling the Complexity of Ginger Rhizome Rot Disease: A Focus on Pathogen Interactions. Journal of Phytopathology 2024, 172 (5), e13392. DOI: 10.1111/jph.13392