Metallic oxide nanoparticles enhance lead stress tolerance in Pearl millet (Pennisetum glaucum L.) by improving morpho–physio–biochemical traits

Nanotechnology represents an innovative approach to ameliorating abiotic stress in pearl millet (Pennisetum glaucum L.) with the application of Copper oxide (CuO - NPs) Titanium dioxide (TiO₂-NPs) and Silicon dioxide (SiO₂-NPs) gaining notable popularity recently. Therefore, we have utilized CuO, TiO₂, and SiO₂ nanoparticles at a concentration of 100 mg L⁻¹ as alleviating agents on P. glaucum grown in soil supplemented with varying levels of lead (Pb) at 0, 100, and 200 mg kg⁻¹ (applied as Pb(NO₃)₂). This study investigates various growth - related attributes, the efficiency of the photosynthetic machinery, indicators of oxidative stress, and responses of both enzymatic and non-enzymatic antioxidants, along with their specific gene expression, sugar content, AsA - GSH cycle, cellular fractionation, proline metabolism and Pb accumulation in different parts of the plant. Our results showed that the Pb toxicity in the soil showed a significant declined in the growth, gas exchange attributes, sugars, AsA - GSH cycle, cellular fractionation, proline metabolism in P. glaucum. However, Pb toxicity significantly increased oxidative stress biomarkers, enzymatic and non-enzymatic antioxidants including their gene expression in P. glaucum seedlings. Although, the application of CuO, TiO₂ and SiO₂ NPs showed a significant increase in the plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds and their gene expression and also decreased the oxidative stress. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.