Silicon efflux transporter involved in silicon transport in shoots. In the nodes, involved with LSI2 and NIP2-2/LSI6 in silicon intervascular transfer, which is required for the preferential distribution of silicon, such as hyperaccumulation of silicon in the husk. 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. Belongs to the arsenite-antimonite (ArsB) efflux (TC 2.A.45) family.