Steroidal glycoalkaloids (SGAs), such as α-solamargine and α-solamarine, are phytoanticipins commonly found in solanaceous plants, exhibiting strong nematicidal properties against Globodera pallida, a major pest of potato. Solanum sisymbriifolium, a known trap crop for G. pallida, produces solasodine-type SGAs and has substantial efficacy in reducing the G. pallida population. To date, their suppressive effects on hatch and reproduction are well-documented, but their role in inducing oxidative stress remains unexplored. In the present study, second-stage (J2s) G. pallida were exposed to the SGAs compounds (α-solamargine and α-solamarine) and hexane/ butanol root and shoot extract of S. sisymbriifolium for different time intervals (0 to 24h). Intracellular reactive oxygen species (ROS) levels were quantified using H2DCFDA-based fluorescence microscopy. All the treatments significantly elevated ROS levels compared to untreated control. To further assess the oxidative imbalance, the activity of the oxidative enzymes, Glutathione-S-transferase (GST) and catalase were measured. Additionally, qRT-PCR analysis revealed a significant upregulation of antioxidant and detoxification-related genes (gp-gst-1, gp-cyp-33C9, and gp-sod-3) compared to the untreated control, indicating a stress response triggered by oxidative imbalance. The results demonstrate that SGAs and extracts from S. sisymbriifolium not only interfere with the life cycle of G. pallida but also induce oxidative stress, which may contribute to their nematicidal action by reducing viability, infectivity, and reproduction. Understanding the roles of ROS as a stress-mediated mechanism provides a valuable framework in the development of bionematicides, which target the redox homeostasis in plant-parasitic nematodes.
