Poster: Intracellular Signaling
Abs #
832: Phenotypes of Arabidopsis thaliana with Altered Glutathione Metabolism
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Presenter: |
Henmi, Kenji , k_henmi@bio-ribs.com |
Authors | Henmi, Kenji (A) Masaki, Iwabuchi (A) KenŐichi, Ogawa (A) | | Affiliations: |
(A): Research Institute for Biological Sciences, Okayama (RIBS)
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It has been known that the antioxidant glutathione (GSH) plays roles in protection from oxidative stress and detoxification of xenobiotics, and we have recently shown that it is also required for plant developmant. However, the mechanisms are not fully understood. GSH exerts the redox buffering action in the plant cells, and this action might account for the mechanisms. This idea is not inconsistent with our previous report that changes in the levels of GSH and its oxidized form (GSSG) are necessary for the transdifferentiation of mesophyll cells into tracheary elements (TEs) in the Zinnia experimental system [Henmi, K. et al. (2001) Plant Cell Physiol. 42: 673]. To verify a significance of the cellular redox status of glutathione in cell differentiations and stress responses, we investigated the phenotypes of plants with altered glutathione metabolism. Transgenic Arabidopsis plants overexpressing dehydroascorbate reductase that oxidizes GSH, or glutathione reductase (GR) that regenerates GSH from GSSG, showed retarded root formation and reduced number of cells located in the root meristemaic region, compared to those of non-transgenic plant. These results suggest that changes in the redox status regulates other cell differentiations as well as the TE differentiation in planta. Under photostressful conditions, the levels of anthocyanin accumulation in GR-overexpressing plants were lower than those in non-transgenic plant, suggesting that regulation of anthocyanin accumulation also depends on changes in the redox status. However, there were little differences in sensitivity to Cd2+ between the transgenic and non-transgenic plants, suggesting that tolerance against Cd2+ relies on glutathione level itself, not on changes in the redox status.
