Water channel required to facilitate the transport of water across cell membrane. Increases the capacity for root water uptake under water deficit. May play a role in drought avoidance in upland rice. Expressed in roots and leaves. By water deficit in upland rice. Expression decreased by water deficit in lowland rice. Circadian-regulation. Expression is higher during the light phase than during the dark phase. 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. PIP (TC 1.A.8.11) subfamily.