OsPIP2;3 as an aquaporin contributes to rice resistance to water deficit but not to salt stress

Plant aquaporins are a class of membrane intrinsic channels that predominantly transport water and function in adaptation to drought and salinity stresses. Many aquaporins are reported in a verity of planta, but their biological functions and mechanisms for coordinating water movement are largely unknown. In this study we identified a functionally uncharacterized PIP2 subfamily gene OsPIP2;3 involved in rice water deficit and salt stress responses. OsPIP2;3 was targeted to the plasma membrane and mainly expressed in roots throughout the life span. OsPIP2;3 was substantially upregulated under osmotic and salt stresses. The tolerance of OsPIP2;3 under water deficit was demonstrated in the transgenic rice overexpressing OsPIP2;3 that significantly enhanced the plant growth, with tissue elongation, fresh biomass, and chlorophyll accumulation. The increased adaptation to water deficit was associated with the physiological responses, exhibiting the lower degree of drought-induced cellular damage including electrolyte leakage, reactive oxygen species (O-2(-) and H2O2), peroxides (malondialdehyde), and higher survival rate, water holding capacity and proline accumulation. In contrast, OsPIP2;3 knockdown (RNA interference, RNAi) resulted in the growth retard and physiological defects. Both OsPIP2;3 overexpression (OE) and RNAi lines did not show evident effects on the root and shoot elongation, plant biomass, and Na+ or K+ concentrations in rice under salt stress, implying that OsPIP2;3 is not involved in salt stress response. Collectively, these studies point out that OsPIP2;3 as an aquaporin contributes to the adaptation of rice to water-limiting but not to salinity environment.

Automated summary

The study identified an uncharacterized aquaporin gene OsPIP2;3 involved in rice water deficit and salt stress responses, enhancing plant growth and physiological adaptations under water deficit.