Glutathione levels control glucose-6-phosphate dehydrogenase activity during elicitor-induced oxidative stress in cell suspension cultures of Taxus chinensis

Fungal elicitor from Aspergillus niger simultaneously induced H2O2 accumulation and increased activity of glucose-6-phosphate dehydrogenase (G6PDH), glutathione reductase (GR) and galutathione peroxidase (GP) in cell suspension cultures of Taxus chinensis. H2O2 accumulation was abolished by the inactivation of G6PDH, which was similar to the NADPH oxidase inhibitors diphenylene iodonium, imidazole, and pyridine did. Exogenous H2O2 and generators of superoxide anions enhanced G6PDH activity; however, the enhanced G6PDH activity was suppressed by the glutathione (GSH) precursor N-acetylcysteine (NAC). Moreover, buthionine sulfoximine, an inhibitor of GSH synthase. had little effect on H2O2 production, but a significant increase in G6PDH activity and a decrease in GSH level compared with only fungal elicitor. These data showed that G6PDH activation was dependent on decreased GSH pool. Catalase inhibitor aminotriazole had little effect on fungal elicitor-induced GSH level and G6PDH activity, indicating decreased GSH pool was independent of catalase. (C) 2004 Elsevier Ireland Ltd. All rights reserved.