H(2) Enhances Arabidopsis Salt Tolerance by Manipulating ZAT10/12-Mediated Antioxidant Defence and Controlling Sodium Exclusion

BACKGROUND: The metabolism of hydrogen gas (H(2)) in bacteria and algae has been extensively studied for the interesting of developing H(2)-based fuel. Recently, H(2) is recognized as a therapeutic antioxidant and activates several signalling pathways in clinical trials. However, underlying physiological roles and mechanisms of H(2) in plants as well as its signalling cascade remain unknown. METHODOLOGY/PRINCIPAL FINDINGS: In this report, histochemical, molecular, immunological and genetic approaches were applied to characterize the participation of H(2) in enhancing Arabidopsis salt tolerance. An increase of endogenous H(2) release was observed 6 hr after exposure to 150 mM NaCl. Arabidopsis pretreated with 50% H(2)-saturated liquid medium, mimicking the induction of endogenous H(2) release when subsequently exposed to NaCl, effectively decreased salinity-induced growth inhibition. Further results showed that H(2) 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, H(2) 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 H(2) signalling. CONCLUSIONS: Overall, our findings indicate that H(2) 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.