Global warming severely challenges sweet potato cultivation by disrupting physiological, biochemical, and structural processes. The potential of glutathione-gold nanoclusters (GSH-Au NCs) in enhancing thermotolerance remains largely unexplored in vegetable sweet potato, a key industrial and food security crop. We hypothesized that foliar application of GSH-Au NCs would mitigate heat-induced disruptions in photosynthesis, redox homeostasis, and cellular structures by enhancing antioxidant defenses and enzymatic activities. Under controlled heat stress (42 °C day/35°C night for 7 days), heat stress diminished shoot biomass, leaf area, RWC, and root biomass, while impairing photosynthesis and elevating oxidative damage (H2O2: 276.7% and MDA: 481.5%) and electrolyte leakage by 85.7%. GSH-Au NCs (2 mg L− 1) reversed these effects, enhancing growth, shoot and root biomass (45.3% and 28.3%), and RWC (7.9%). These improvements were associated with enhanced photosynthetic efficiency through elevated chlorophyll content (72.6%), Rubisco activity (26.4%), gas exchange parameters (Pn: 86.1% and Gs: 389%), and chlorophyll fluorescence (Fv/Fm: 16.0% and ETR: 48.2%). Mechanistically, GSH-Au NCs correlated with upregulation of ascorbate-glutathione (AsA-GSH) cycle, boosting enzymatic (SOD: 30.1%, APX: 33.6%, and GR: 20.9%) and non-enzymatic antioxidants (AsA/DHA: 33.8% and GSH/GSSG: 29.1%), while lowering oxidative markers: H2O2 (37.8%), MDA (51.7%), and EL (26.8%), compared with heat stressed plants without NCs treatment. Transcriptional upregulation of SOD, APX, GR, DHAR, and MDHAR genes supported these effects. Additionally, GSH-Au NCs enhanced glyoxalase activity (Gly I: 36.9% and Gly II: 35.0%), reducing toxic methylglyoxal (29.3%). Higher proline (51.7%) and secondary metabolites (polyphenols: 38.3% and flavonoids: 62.9%) further strengthen stress resilience. Moreover, GSH-Au NCs restored stomatal behavior and preserved chloroplast and mitochondrial structure. These findings highlight GSH-Au NCs (2 mg L− 1) as a sustainable, cost-effective, eco-friendly nanobiotechnological strategy for mitigating heat stress in sweet potato and promoting climate-resilient horticulture, advancing beyond prior studies on individual GSH or Au nanomaterials by demonstrating the synergetic effects of their combined nanocluster form for the first time in plant species.
Kumar et al. (2026) studied this question.