Uptake of Silicon in Different Plant Species

Silicon (Si) is the second most abundant element in soil, and has a wide array of functions in the growth and development of plants. Silicon is able to alleviate various stresses including diseases, pests, lodging, drought, and nutrient imbalance. Although all plants contain some Si in their tissues, the concentrations of Si in the shoots differ greatly with plant species, and this difference is attributed to the capacity of the roots to take up Si. At least two steps are involved in Si uptake, including radial transport from external solution to the root cells, and subsequent release from the root cells to the xylem. Currently, the latter process seems more important for high Si accumulation. The first gene encoding Si transporter has recently been identified in rice, a typical Si-accumulating plant. The transporter encoded by this gene shows a high specificity for Si, and is localized at the distal side of both exodermis and endodermis. The future cloning of more genes will help in our understanding of the molecular mechanisms of Si uptake in different plant species.