Molecular Identification and Pathogenic Impact of Pythium aphanidermatum on Ginger (Zingiber officinale): Insights into Oxidative Stress, Antioxidant Responses, and Mycotoxin Profiling

Mukesh Meena^1*Garima Yadav¹Priyankaraj Sonigra¹Tushar Mehta¹Adhishree Nagda¹Abhishek Sahoo¹Prashant Swapnil²

• ¹Mohanlal Sukhadia University, Udaipur, India
• ²Central University of Punjab, Bathinda, Punjab, India

Ginger (Zingiber officinale) is an economically significant crop, widely cultivated for its medicinal and culinary applications. However, its production is severely affected by fungal pathogens, particularly Pythium aphanidermatum, which cause substantial yield losses and quality deterioration. This study aimed to identify fungal pathogens associated with ginger rhizome rot through molecular characterization and evaluate their impact on plant physiological and biochemical responses. Fungal isolates were obtained from infected rhizomes and subjected to morphological and molecular identification using ITS1 and ITS4 primers. Pathogenicity was assessed through in vitro and in vivo assays, including oxidative stress analysis and enzymatic activity measurements. The results confirmed the presence of P. aphanidermatum, which triggered significant oxidative stress responses in infected plants. The infection led to increased reactive oxygen species (ROS) accumulation, lipid peroxidation, and chlorophyll degradation. Antioxidant enzyme activities, including ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR), were significantly upregulated in response to fungal stress, with F1 treatment demonstrating the most effective mitigation of oxidative damage. Additionally, phenolic metabolism enzymes, phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO), exhibited substantial increases in treated plants, indicating enhanced defense responses. Mycotoxin profiling using column chromatography and gas chromatography-mass spectrometry (GC-MS) identified key secondary metabolites contributing to fungal pathogenicity. The study concludes that fungal infections impose severe oxidative stress on ginger plants, the present study demonstrates that Pythium aphanidermatum causes severe oxidative stress and physiological damage in ginger plants, as evidenced by elevated levels of ROS, MDA, and disrupted chlorophyll composition. Application of fungal crude extracts (F1–F3), 24 hours prior to pathogen inoculation, significantly reduced oxidative damage and helped maintain plant physiological integrity. These findings provide insight into the pathogenic mechanisms of P. aphanidermatum and the phytotoxic potential of its metabolites. The study lays the groundwork for future research on detailed chemical characterization of bioactive fractions and the validation of these findings under natural field conditions. but timely treatment interventions effectively reduce cellular damage and enhance plant resilience. These findings provide valuable insights into fungal pathogenesis and offer potential strategies for developing integrated disease management practices to improve ginger crop health and productivity.