title: Change in the redox state of glutathione regulates differentiation of tracheary elements in Zinnia cells and Arabidopsis roots.
abstract: Exogenously applied GSH and GSSG can control the in vitro differentiation of mesophyll cells to tracheary elements (TEs) in Zinnia elegans, and de novo GSH synthesis is essential for the early differentiation. The purpose of the present study is to address how GSH and GSSG control TE differentiation. GSSG transiently accumulated during the in vitro TE differentiation and exogenously applied GSSG down-regulated transcript levels of GSSG reductase (GR), an enzyme maintaining glutathione in a reduced redox state, while there were no significant changes in transcript levels of enzymes involved in GSH synthesis. Transgenic Arabidopsis overexpressing the GR gene showed delayed TE formation in the root, which was attributed to the suppression of cell division. Exogenously applied GSH had an effect similar to overexpression of the GR gene. These findings suggest that reduced states of glutathione suppress TE differentiation. In wild-type Arabidopsis, TE formation was promoted by application of GSSG at an appropriate concentration, but was suppressed at higher concentrations. A T-DNA-inserted knockout mutant of cytosolic GR exhibited delayed TE formation; this phenotype was little affected by GSSG application. Taken together, the process of the redox changes in glutathione is considered to be controlled via GR activity for TE differentiation.
authors.affiliation: Research Institute for Biological Sciences (RIBS), Okayama, Kibichuo-cho, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Henmi
authors.forename: Taku
authors.initials: T
authors.lastname: Demura
authors.forename: Seiji
authors.initials: S
authors.lastname: Tsuboi
authors.forename: Hiroo
authors.initials: H
authors.lastname: Fukuda
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwabuchi
authors.forename: Ken'ichi
authors.initials: K
authors.lastname: Ogawa
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D019659:Asteraceae / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D002454:Cell Differentiation; D005978:Glutathione / Q000096:biosynthesis / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005980:Glutathione Reductase; D005978:Glutathione; D019803:Glutathione Disulfide