H2 Enhances Arabidopsis Salt Tolerance by Manipulating ZAT10/12-Mediated Antioxidant Defence and Controlling Sodium Exclusion

BackgroundThe metabolism of hydrogen gas (H2) in bacteria and algae has been extensively studied for the interesting of developing H2-based fuel. Recently, H2 is recognized as a therapeutic antioxidant and activates several signalling pathways in clinical trials. However, underlying physiological roles and mechanisms of H2 in plants as well as its signalling cascade remain unknown. Methodology/Principal FindingsIn this report, histochemical, molecular, immunological and genetic approaches were applied to characterize the participation of H2 in enhancing Arabidopsis salt tolerance. An increase of endogenous H2 release was observed 6 hr after exposure to 150 mM NaCl. Arabidopsis pretreated with 50% H2-saturated liquid medium, mimicking the induction of endogenous H2 release when subsequently exposed to NaCl, effectively decreased salinity-induced growth inhibition. Further results showed that H2 pretreatment modulated genes/proteins of zinc-finger transcription factor ZAT10/12 and related antioxidant defence enzymes, thus significantly counteracting the NaCl-induced reactive oxygen species (ROS) overproduction and lipid peroxidation. Additionally, H2 pretreatment maintained ion homeostasis by regulating the antiporters and H+ pump responsible for Na+ exclusion (in particular) and compartmentation. Genetic evidence suggested that SOS1 and cAPX1 might be the target genes of H2 signalling. ConclusionsOverall, our findings indicate that H2 acts as a novel and cytoprotective regulator in coupling ZAT10/12-mediated antioxidant defence and maintenance of ion homeostasis in the improvement of Arabidopsis salt tolerance.