The roles of H 2 S and H 2 O 2 in regulating AsA-GSH cycle in the leaves of wheat seedlings under drought stress

This paper investigated the roles of hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) and the possible relationship between them in regulating the AsA-GSH cycle in wheat leaves under drought stress (DS). Results showed that DS markedly increased the production of H2S and H2O2, the transcript levels and activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR); malondialdehyde (MDA) content; and electrolyte leakage (EL). Meanwhile, DS markedly reduced plant height and biomass. Above increases induced by drought stress except MDA content and EL were all suppressed by pretreatments with H2S synthesis inhibitor aminooxyaceticacid (AOA) and H2O2 synthesis inhibitor diphenylene iodonium (DPI). Besides, pretreatments with AOA and DPI further significantly increased MDA content and EL and significantly reduced plant height and biomass under DS. DPI reduced the production of H2O2 and H2S induced by DS. AOA also reduced the production of H2S and H2O2 induced by DS. Pretreatments with NaHS + AOA and H2O2 + DPI reversed above effects of AOA and DPI. Our results suggested that H2S and H2O2 all participated in the up-regulation of AsA-GSH cycle in wheat leaves by DS and possibly affected each other.