Boric acid transporter. Low water transport activity. Plays an important role as plasma membrane boric acid channel for the boron uptake required for plant growth and development under boron limitation. Expressed in rosette leaves. By boron limitation in the root elongation and the root hair zones. Aquaporins contain two tandem repeats each containing three membrane-spanning domains and a pore-forming loop with the signature motif Asn-Pro-Ala/Ser/Val (NPA). Plants display lower boric acid uptake into roots, lower biomass production, and increased sensitivity of root and shoot development to boron deficiency. Belongs to the MIP/aquaporin (TC 1.A.8) family. NIP (TC 1.A.8.12) subfamily.