Exogenous hesperidin orchestrates antioxidant defense, osmolyte metabolism, and nutrient homeostasis to mitigate heavy metal toxicity in canola.

Heavy metal contamination of agricultural soils severely impairs plant physiological function by disrupting nutrient uptake, photosynthesis, and redox homeostasis. Previous studies have established that heavy metals such as cadmium (Cd), chromium (Cr), lead (Pb), and copper (Cu) induce oxidative stress, membrane damage, and metabolic imbalance in plants, and that flavonoids can act as antioxidants to mitigate some of these effects. However, the specific mechanistic role of hesperidin in regulating plant physiological responses under heavy metal stress in canola remains unclear. In this study, we investigated the effects of exogenous hesperidin application on canola (Brassica napus L.) exposed to Cd, Cr, Pb, and Cu stress. Hesperidin treatment enhanced enzymatic antioxidant systems, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as non-enzymatic antioxidants, thereby reducing reactive oxygen species (ROS) accumulation and stabilizing membrane integrity. In addition, hesperidin regulated osmolyte metabolism (proline and soluble sugars) and restored ion homeostasis, leading to improved nutrient acquisition and photosynthetic efficiency. These coordinated responses demonstrate that hesperidin functions as a physiological regulator, integrating antioxidant defense and metabolic adjustment to confer resilience against heavy metal toxicity. The novelty of this work lies in identifying hesperidin's dual role in modulating both redox balance and osmolyte metabolism, thereby providing new mechanistic insight into flavonoid-mediated stress tolerance. Our findings highlight hesperidin as a potential biotechnological tool to improve crop performance and resilience in contaminated environments.