“Nano-calcium L-Aspartate enhances rice tolerance to arsenic toxicity by improving nitrogen metabolism, cell wall sequestration, and antioxidant system”

Rice is one of the major sources of human exposure to arsenic (As), and its contamination is a critical issue for crop productivity and human health. Herein, we investigated how nano-calcium L-aspartate (nano-Ca) nanoparticles alleviate As-induced toxicity in rice (Oryzae sativa L.) seedlings. The results showed that As stress restricted rice growth and increased the concentration of As in roots and shoots. Application of nano-Ca markedly improved seedling growth, including biomass, photosynthetic pigment content, and antioxidant enzyme activity. As a result, Nano-Ca decreased As concentrations in shoots and roots by 67.04 % and 22.78 %, respectively, primarily due to the increasing accumulation of As in pectin and hemicellulose. Furthermore, nano-Ca elevated the activity of nitrogen-metabolizing enzymes. The treatment also promoted demethylation of pectin, which enhanced its As-binding capability. Additionally, nano-Ca enhanced proline metabolism, also provided antioxidant defenses, and regulated calcium homeostasis, which help mitigate oxidative damage characteristics like malondialdehyde and hydrogen peroxidation. As these findings demonstrated, nano-Ca could be an efficient, friendly means of alleviating As toxicity in rice, offering an environmentally sustainable option for agricultural strategies in the arsenic-contaminated areas.