title: Redox state of low-molecular-weight thiols and disulphides during somatic embryogenesis of salt-treated suspension cultures of Dactylis glomerata L.
abstract: The tripeptide antioxidant γ-L-glutamyl-L-cysteinyl-glycine, or glutathione (GSH), serves a central role in ROS scavenging and oxidative signalling. Here, GSH, glutathione disulphide (GSSG), and other low-molecular-weight (LMW) thiols and their corresponding disulphides were studied in embryogenic suspension cultures of Dactylis glomerata L. subjected to moderate (0.085 M NaCl) or severe (0.17 M NaCl) salt stress. Total glutathione (GSH + GSSG) concentrations and redox state were associated with growth and development in control cultures and in moderately salt-stressed cultures and were affected by severe salt stress. The redox state of the cystine (CySS)/2 cysteine (Cys) redox couple was also affected by developmental stage and salt stress. The glutathione half-cell reduction potential (E(GSSG/2 GSH)) increased with the duration of culturing and peaked when somatic embryos were formed, as did the half-cell reduction potential of the CySS/2 Cys redox couple (E(CySS/2 Cys)). The most noticeable relationship between cellular redox state and developmental state was found when all LMW thiols and disulphides present were mathematically combined into a 'thiol-disulphide redox environment' (E(thiol-disulphide)), whereby reducing conditions accompanied proliferation, resulting in the formation of pro-embryogenic masses (PEMs), and oxidizing conditions accompanied differentiation, resulting in the formation of somatic embryos. The comparatively high contribution of E(CySS/2 Cys) to E(thiol-disulphide) in cultures exposed to severe salt stress suggests that Cys and CySS may be important intracellular redox regulators with a potential role in stress signalling.
authors.affiliation: Department of Biochemistry, Sofia University, Sofia, Bulgaria.
authors.forename: Lyuben
authors.initials: L
authors.lastname: Zagorchev
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Seal
authors.forename: Ilse
authors.initials: I
authors.lastname: Kranner
authors.forename: Mariela
authors.initials: M
authors.lastname: Odjakova
mesh_terms: D049109:Cell Proliferation; D002478:Cells, Cultured; D003545:Cysteine / Q000378:metabolism; D003553:Cystine / Q000378:metabolism; D031745:Dactylis / Q000254:growth & development* / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D009997:Osmotic Pressure; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D059828:Plant Cells / Q000378:metabolism; D058439:Plant Somatic Embryogenesis Techniques; D017382:Reactive Oxygen Species; D012965:Sodium Chloride / Q000737:chemistry / Q000494:pharmacology; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D012965:Sodium Chloride; D003553:Cystine; D005978:Glutathione; D003545:Cysteine; D019803:Glutathione Disulfide