Effects of exogenous mineral silicon on physiological characteristics and arsenic uptake and transport in rice

Soil arsenic (As) contamination poses a significant threat to food security and human health. Diatomaceous earth (DE) as a representative exogenous mineral silicon can effectively regulate the migration and transformation of As in the soil-rice system. However, the mechanisms underlying the effects of DE application on As uptake, translocation, and stress regulation in rice remain unclear. In this study, pot experiments were conducted to investigate the effects of applying different amounts of DE on As uptake, translocation, and key physiological and biochemical indicators in rice. The results demonstrated that the application of DE significantly inhibited As uptake and translocation in rice, and reduced As content in brown rice by 40.96-85.88 %. The application of DE promoted As adsorption by iron plaque formation on rice root surface, increased the capacity of cell wall for As immobilization, and promoted greater As accumulation in husk by regulating the expression of transporter genes, thereby reducing As content in brown rice. The application of DE regulated antioxidant enzyme activities, and alleviated the toxic effects of As in rice. This study has deepened our understanding of the mechanisms by which DE inhibits As uptake and translocation in rice, and provided more biological knowledge for reducing arsenic accumulation and mitigating As stress in rice.