Cerium dioxide nanoparticles protect Catharanthus roseus against arsenic (As) toxicity by enhancing oxidative tolerance, modulating gene expression and minimizing As uptake.

Arsenic (As) is a toxic metalloid, and its increasing contamination in soil has become an important public health concern. Nevertheless, cerium dioxide nanoparticles (CeO₂ NPs) have shown potential for phytostabilization of metal polluted soil. Currently during pot trial, As toxicity (As30, As70 mg kg⁻¹) decreased growth, photosynthetic pigments, gas exchange attributes, membrane stability indices (MSIs) and relative water contents (RWCs) of Catharanthus roseus. Moreover, As stress obviously increased, malondialdehyde (MDA), As, and hydrogen peroxide (H₂O₂) levels in C. roseus plants. Conversely, the application of CeO₂ NPs (80 mg L⁻¹) significantly improved the antioxidant system of C. roseus and augmented growth attributes, synthesis of photosynthetic pigments, proline content, and gas exchange attributes, in addition to modulating the expression of stress-related genes (STR, DAT, PRX1 and GS) under As-stressed conditions. Foliar application of CeO₂ NPs reduced the uptake and translocation of As from the soil to plant tissues. Furthermore, exogenous CeO₂ NPs supply significantly reduced the MDA (21.2%), H₂O₂ (10.2%), and declined As uptake in the shoot (25.3%) and root (17.7%) tissues of the C. roseus plants exposed to higher As70 stress. Hence, CeO₂ NPs showed great potential for improvement of growth and alleviation of As toxicity in C. roseus plants.