# Cerium oxide nanoparticles enhance rice productivity by modulating nitric oxide signaling, carbon metabolism, and potassium homeostasis under chromium-induced environmental stress

## TL;DR

Cerium oxide nanoparticles help rice plants grow better under chromium stress by reducing oxidative damage and improving metabolism.

## Contribution

This study demonstrates the novel use of cerium dioxide nanoparticles to mitigate chromium toxicity in rice through multiple physiological mechanisms.

## Key findings

- Chromium stress increased oxidative markers like TBARS, H2O2, and methylglyoxal by 49-67%.
- CeO2 NPs reduced oxidative stress and boosted antioxidant enzyme activity in rice plants.
- CeO2 NPs improved rice growth, biomass, and key metabolic processes like starch and chlorophyll levels.

## Abstract

Chromium (Cr) contamination in agricultural soils represents a serious challenge to rice productivity and food security, underscoring the need for innovative approaches to improve Cr-tolerance and alleviate its detrimental effects on plant growth and development. Recently, nanotechnology has been increasingly used to improve the tolerance of plants exposed to metal stress. In view of the beneficial roles of nanoparticles in mitigating metal stress in plants, this study was conducted to assess the effectiveness of cerium dioxide nanoparticles (CeO2 NPs) in alleviating Cr-induced toxicity in rice plants. Chromium stress (100 µM) and CeO2 NPs (100 ppm) were applied at the seed stage by soaking the seeds in their respective solutions for 12 h prior to sowing. Chromium stress markedly increased the contents of thiobarbituric acid-reactive substances (TBARS) by 67%, hydrogen peroxide (H2O2) by 62%, superoxide anion (O2•-) by 58%, and methylglyoxal (MG) by 63% compared with control plants. In contrast, Cr stress significantly reduced the concentrations of starch (51%), sucrose synthase (49%), amylase (68%), chlorophyll (69%), and RuBisCO (67%). However, the application of CeO2 NPs markedly enhanced plant growth and biomass accumulation, alleviated oxidative stress, and stimulated antioxidant enzyme activities in rice plants subjected to Cr stress. Overall, these results demonstrate that the application of CeO2 effectively alleviates Cr-induced stress in rice plants and offers promising prospects for advancing NP-based phytoremediation strategies.