Mitigation of bensulfuron-methyl induced multiple stress responses in Cucumis sativus L. by biostimulants: A comprehensive metabolic and molecular docking approach.
Sulfonylurea herbicides, such as bensulfuron-methyl (BM), are widely used around the world, but they pose a severe risk of phytotoxicity to crop plants that are not the herbicide's target, disrupting their physiological and metabolic homeostasis. Although biostimulants (BS) are increasingly recognised for alleviating abiotic stress, the mechanisms by which they mitigate herbicide toxicity across multiple pathways remain poorly investigated. This study comprehensively elucidates the morphological, physiological, biochemical, cytogenetic and molecular responses of cucumber (Cucumis sativus L.) seedlings to BM toxicity, as well as the restorative capacity of an amino acid-based BS. Our findings demonstrate that exposure to BM significantly suppresses plant biomass and triggers severe oxidative stress, as evidenced by the excessive accumulation of reactive oxygen species (ROS; H₂O₂ and malondialdehyde (MDA)). This systemic toxicity severely disrupted nutritional homeostasis and phytohormone profiles, notably inhibiting the biosynthesis of indole-3-acetic acid (IAA), gibberellic acid (GA) and salicylic acid (SA) while increasing abscisic acid (ABA). Conversely, the application of exogenous BSs effectively reversed these phytotoxic damages by upregulating antioxidant defence enzymes (SOD, CAT and POD) and restoring mineral uptake and hormonal networks. Furthermore, anatomical and cytogenetic assessments in Allium cepa revealed that BM induced structural deformations and chromosomal aberrations, which were significantly mitigated by BS pretreatment. Molecular docking simulations confirmed that BM exerts its toxicity by directly binding to essential proteins (e.g. ICL, CAT and POD) and DNA structures, thereby blocking their normal functions. In conclusion, this study provides profound mechanistic insights into the multiple stress responses induced by BM and reveals the ability of amino acid-based BSs to mitigate the effects of herbicide contamination, offering a sustainable strategy to protect agricultural productivity.