Green synthesized silver quantum dot mitigate arsenic translocation in spinach via glutathione-driven redox balance and modulation of stomatal-transpiration dynamics

• Green-synthesized silver quantum dots (Ag-QDs) effectively alleviated arsenic (As) induced toxicity in spinach. • Ag-QDs attenuate As translocation in spinach by modulating stomatal conductance and transpiration dynamics. • Ag-QDs maintained steady state equilibrium between reactive oxygen species and antioxidant machinery under As stress. • Ag-QDs limit As accumulation through the regulation of glutathione-mediated redox homeostasis. Soil contamination by toxic heavy metals, particularly arsenic (As), poses a significant threat to agricultural productivity and global food security. To address this, plant scientists have explored various strategies to enhance As tolerance, including the use of external agents to mitigate As induced oxidative stress. In this study, a green synthesis approach was employed to evaluate the potential of phytosynthesized silver quantum dots (Ag-QDs) in modulating physio-chemical responses associated with As stress tolerance in spinach plant. The experiment investigated the effects of varying As concentrations (0, 25, and 50 µM) in soil, with and without Ag-QDs supplementation (0, 10, 20, and 30 µM), on growth attributes, chlorophyll content, stomatal characteristics, oxidative stress biomarkers, antioxidant defense, and As accumulation. As induced toxicity led to pronounced cellular membrane damage, as indicated by elevated malondialdehyde (MDA), increased electrolyte leakage (EL), and higher hydrogen peroxide (H 2 O 2 ) levels, ultimately suppressing plant growth. Additionally, As exposure impaired stomatal behavior, transpiration rate, and antioxidant enzyme activities. However, Ag-QD application significantly (p ≤ 0.05) enhanced the activity of antioxidant enzymes: ascorbate peroxidase (APX), superoxide dismutase (SOD), and glutathione reductase (GR), alongside increased levels of reduced glutathione (GSH). Application of Ag-QDs also improved stomatal traits and reduced As accumulation in plant tissues. These findings suggest that Ag-QDs alleviate As toxicity by modulating glutathione-mediated redox homeostasis, restricting As translocation, and regulating stomatal-transpiration dynamics, thereby enhancing plant growth and stress resilience.