Ectopic expression of a rice plasma membrane intrinsic protein (OsPIP1;3) promotes plant growth and water uptake

Plasma membrane intrinsic proteins (PIPs) are known to be major facilitators of the movement of a number of substrates across cell membranes. From a drought‐resistant cultivar of Oryza sativa (rice), we isolated an OsPIP1;3 gene single‐nucleotide polymorphism (SNP) that is mostly expressed in rice roots and is strongly responsive to drought stress. Immunocytochemistry showed that OsPIP1;3 majorly accumulated on the proximal end of the endodermis and the cell surface around the xylem. Expression of GFP‐OsPIP1;3 alone in Xenopus oocytes or rice protoplasts showed OsPIP1;3 mislocalization in the endoplasmic reticulum (ER)‐like neighborhood, whereas co‐expression of OsPIP2;2 recruited OsPIP1;3 to the plasma membrane and led to a significant enhancement of water permeability in oocytes. Moreover, reconstitution of 10×His‐OsPIP1;3 in liposomes demonstrated water channel activity, as revealed by stopped‐flow light scattering. Intriguingly, by patch‐clamp technique, we detected significant NO₃^? conductance of OsPIP1;3 in mammalian cells. To investigate the physiological functions of OsPIP1;3, we ectopically expressed the OsPIP1;3 gene in Nicotiana benthamiana (tobacco). The transgenic tobacco plants exhibited higher photosynthesis rates, root hydraulic conductivity (Lp_r) and water‐use efficiency, resulting in a greater biomass and a higher resistance to water deficit than the wild‐type did. Further experiments suggested that heterologous expression of OsPIP1;3 in cyanobacterium altered bacterial growth under different conditions of CO₂ gas supply. Overall, besides shedding light on the multiple functions played by OsPIP1;3, this work provides insights into the translational value of plant AQPs.