24-epibrassinolide promotes resilience against arsenic stress via modulating amino acid profiles and mRNA abundance of CYP450 and MRP genes in Zea mays L.

This study investigates the role of 24-epibrassinolide (BR, 10 μM) in mitigating arsenic (As)-induced stress in maize (Zea mays L. cv. 704). Seedlings were exposed to As at concentrations of 0, 5, 10, 25, 50, 100, and 250 μM, with or without BR application. Arsenic exposure increased oxidative damage markers such as MDA and H₂O₂ while BR treatment significantly enhanced antioxidant enzymes activities including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione S-transferase (GST), reducing reactive oxygen species (ROS) levels, and minimizing oxidative damage. Additionally, BR significantly increased proline, phenolic compounds, flavonoids, and soluble sugars, contributing to osmoprotection and stress tolerance, as well as enhancing FRAP and DPPH antioxidant activities. Furthermore, BR increased amino acids (AAs) such as proline (Pro), cysteine (Cys), glutamine (Gln), and glutamate (Glu). Gene expression analysis revealed significant upregulation of detoxification-related genes including cytochrome P450 monooxygenases (CYPs), GT1, GST27 and multidrug resistance-associated proteins (MRPs) under BR treatment. These findings suggest that BR enhances maize tolerance to As toxicity by activating detoxification pathways, improving antioxidant defense, and stabilizing metabolic processes. The results underscore the potential application of BR in sustainable agriculture to improve crop resilience in As-contaminated soils.