Silicon transporter involved in the distribution of silicon in shoots. Is responsible for the transport of silicon from the xylem to the leaf tissues. 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 (PubMed:18515498). In the nodes, involved with LSI2 and LSI3 in silicon intervascular transfer, which is required for the preferential distribution of silicon, such as hyperaccumulation of silicon in the husk (PubMed:26283388). Expressed at low levels in roots and leaves (PubMed:16033806). Expressed in roots, leaf sheaths and leaf blades. In roots, it localizes in the plasma membrane of all cells of the young region and is more abundant on the distal side than the proximal side (at protein level). Expressed only in the xylem parenchyma cells adjacent to vessels in both leaf sheaths and leaf blades (at protein level). Is more abundant on the side facing the vessel (at protein level) (PubMed:18515498). Down-regulated by silicon supply in roots and leaf blades. Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala (NPA). Belongs to the MIP/aquaporin (TC 1.A.8) family. NIP (TC 1.A.8.12) subfamily.