Metalloid Nanomaterials Alleviate Arsenic Phytotoxicity and Grain Accumulation in Rice: Mechanisms of Abiotic Stress Tolerance and Rhizosphere Behavior
Xuesong Cao, Xiaofei Chen, Enyuan Liu, Chuanxi Wang, Xiaona Li, Le Yue, Jason C. White, Zhenyu Wang, Baoshan Xing
Abstract
Nanoenabled agriculture technology exhibits potential in reducing arsenic uptake in rice; however, a systematic understanding of the rice–soil–microorganism process of nanomaterials (NMs) is lacking. Soil amendment of metalloid NMs, including SiO 2, hydroxyapatite, S 0, and Se 0 at 10–100 (0.1–5.0 for Se NMs) mg/kg, increased rice biomass by 76.1–135.8% in arsenic-contaminated soil (17.0 mg/kg) and decreased arsenic accumulation in plant tissues by 9.3–78.2%. The beneficial effects were nanoscale-specific and NMs type- and concentration-dependent; 5 mg/kg Se NMs showed the greatest growth promotion and decrease in As accumulation. Mechanistically, (1) Se NMs optimized the soil bacterial community structure, enhancing the abundance of arsM by 104.2% and subsequently increasing arsenic methylation by 276.1% in rhizosphere compared to arsenic-alone treatments; (2) metabolomic analyses showed that Se NMs upregulated the biosynthesis pathway of abscisic acid, jasmonic acid, and glutathione, with subsequent downregulation of the arsenic transporter-related gene expression in roots by 42.2–73.4%, decreasing the formation of iron plaque by 87.6%, and enhancing the arsenic detoxification by 50.0%. Additionally, amendment of metalloid NMs significantly enhanced arsenic-treated rice yield by 66.9–91.4% and grain nutritional quality. This study demonstrates the excellent potential of metalloid NMs for an effective and sustainable strategy to increase food quality and safety.