Synergistic Modulation of Oxidative Defense Pathways in Bitter Gourd under Chromium Toxicity: Integrating Seed Priming Induced Metabolic Reprogramming with Physiological Resilience

Abstract

Chromium (Cr) contamination poses a persistent threat to agricultural productivity, particularly in regions where industrial discharge continues to percolate into arable soils. Bitter gourd (Momordica charantia L.), known for its high therapeutic value, is highly susceptible to Cr-induced oxidative perturbation. In the present study, we investigated how seed priming with soybean and pumpkin seed extracts orchestrates a coordinated biochemical and physiological response that enhances crop resilience under Cr stress. A greenhouse experiment integrating multiple Cr levels with methanolic and aqueous priming treatments revealed that Cr toxicity markedly suppressed shoot elongation, biomass accumulation, water balance, and photosynthetic pigment synthesis while concurrently increasing the levels of reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA). However, primed seeds presented a reprogrammed metabolic landscape characterized by elevated activities of antioxidant enzymes (SOD, CAT, POD), enriched pools of phenolics, flavonoids, and ascorbic acid, and improved pigment and water status. Aqueous soybean extract at 1 g L⁻¹ emerged as the most potent treatment, nearly restoring photosynthetic integrity and minimizing lipid peroxidation even under high Cr exposure. These findings underscore the synergistic capacity of natural seed extracts to fortify redox buffering systems and stabilize cellular metabolism, offering a sustainable, eco-friendly strategy to mitigate heavy metal toxicity in economically important vegetable crops.

Keywords: Bitter gourd, chromium toxicity, oxidative stress, soybean extract, antioxidant enzymes, stress physiology.