title: Osmopriming-induced salt tolerance during seed germination of alfalfa most likely mediates through H2O2signaling and upregulation of heme oxygenase.
abstract: The present study showed that osmopriming or pretreatment with low H2O2doses (2 mM) for 6 h alleviated salt-reduced seed germination. The NADPH oxidase activity was the main source, and superoxide dismutase (SOD) activity might be a secondary source of H2O2generation during osmopriming or H2O2pretreatment. Hematin pretreatment similar to osmopriming improved salt-reduced seed germination that was coincident with the enhancement of heme oxygenase (HO) activity. The semi-quantitative RT-PCR confirmed that osmopriming or H2O2pretreatment was able to upregulate heme oxygenase HO-1 transcription, while the application of N,N-dimethyl thiourea (DMTU as trap of endogenous H2O2) and diphenyleneiodonium (DPI as inhibitor of NADPHox) not only blocked the upregulation of HO but also reversed the osmopriming-induced salt attenuation. The addition of CO-saturated aqueous rescued the inhibitory effect of DMTU and DPI on seed germination and α-amylase activity during osmopriming or H2O2pretreatment, but H2O2could not reverse the inhibitory effect of ZnPPIX (as HO inhibitor) or Hb (as CO scavenger) that indicates that the CO acts downstream of H2O2in priming-driven salt acclimation. The antioxidant enzymes and proline synthesis were upregulated in roots of seedlings grown from primed seeds, and these responses were reversed by adding DMTU, ZnPPIX, and Hb during osmopriming. These findings for the first time suggest that H2O2signaling and upregulation of heme oxygenase play a crucial role in priming-driven salt tolerance.
authors.affiliation: Biology Department, Science Faculty, Shahrekord University, Shahrekord, Iran. rayhanehamooaghaie@yahoo.com.
authors.forename: Rayhaneh
authors.initials: R
authors.lastname: Amooaghaie
authors.affiliation: Biology Department, Science Faculty, Shahrekord University, Shahrekord, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Tabatabaie
mesh_terms: D004790:Enzyme Induction; D018506:Gene Expression Regulation, Plant; D018525:Germination; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D000455:Medicago sativa / Q000201:enzymology* / Q000254:growth & development; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D064587:Osmoregulation; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D055049:Salt Tolerance; D012639:Seeds / Q000201:enzymology* / Q000254:growth & development; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D010940:Plant Proteins; D006861:Hydrogen Peroxide; D006419:Heme Oxygenase (Decyclizing); D013482:Superoxide Dismutase; D019255:NADPH Oxidases
keywords: CO; Heme oxygenase; Hydrogen peroxide; Osmopriming; Salt acclimation; Signal transduction