The Thellungiella salsuginea Tonoplast Aquaporin TsTIP1;2 Functions in Protection Against Multiple Abiotic Stresses

Examination of aquaporin (AQP) membrane channels in extremophile plants may increase our understanding of plant tolerance to high salt, drought or other conditions. Here, we cloned a tonoplast AQP gene (TsTIP1;2) from the halophyte Thellungiella salsuginea and characterized its biological functions. TsTIP1;2 transcripts accumulate to high levels in several organs, increasing in response to multiple external stimuli. Ectopic overexpression of TsTIP1;2 in Arabidopsis significantly increased plant tolerance to drought, salt and oxidative stresses. TsTIP1;2 had water channel activity when expressed in Xenopus oocytes. TsTIP1;2 was also able to conduct H2O2 molecules into yeast cells in response to oxidative stress. TsTIP1;2 was not permeable to Na+ in Xenopus oocytes, but it could facilitate the entry of Na+ ions into plant cell vacuoles by an indirect process under high-salinity conditions. Collectively, these data showed that TsTIP1;2 could mediate the conduction of both H2O and H2O2 across membranes, and may act as a multifunctional contributor to survival of T. salsuginea in highly stressful habitats.