Mechanisms of Enhanced Heavy Metal Tolerance in Plants by Silicon: A Review

In recent years, due to excessive emission of industrial waste, wastewater irrigation, and unreasonable utilization of fertilizers, pesticides and plastic sheeting, heavy metal pollution is increasing rapidly, resulting in many environmental problems. Silicon (Si), as the second most abundant element in the soil, can not only stimulate plant growth, but alleviate various biotic and abiotic stresses, including heavy metal stress. Here, we reviewed recent advances in the mechanisms for Si-mediated heavy metal tolerance in plants. These mechanisms included reducing active heavy metal ions in growth media, reducing heavy metal transport to the shoot, stimulating enzymatic and non-enzymatic antioxidants, chelation, compartmentation, regulation of the expression of metal transport genes, and structural changes in plants. Further research orientation is also discussed.