Silicon influx transporter responsible for silicon transport from the external solution to the root cells. Is coupled with the silicon efflux transporter LSI2 in both exodermal and endodermal root cells for an efficient silicon transport across the cells into the stele. Silicon is beneficial to plant growth and helps plants to overcome abiotic and biotic stresses by preventing lodging (falling over) and increasing resistance to pests and diseases, as well as other stresses. Is coupled with LSI2 transporter in roots for efficient uptake of arsenite, which is further dispatched in shoots and grains. Mediates uptake of methylated arsenic species in roots