Abstract
Hydrogen peroxide is thought to be an important signal molecule regulating many cellular processes. In higher plants, the homeostasis of H2O2 is maintained mainly by ascorbate peroxidase (APX), which is localized in cytosol and various cell organelles. To investigate the role of cytosolic APX in regulation of cellular redox status and stress response, here we used a transformant cell line of tobacco BY-2 (cAPX-S1) with reduced cytosolic APX activity obtained by introducing Arabidopsis APX1 cDNA. Intracellular H2O2 concentrations, and the TBARS values increased significantly in cAPX-S1 compared to those of the untransformed cells. However, activities of the enzymes involved in the ascorbate-glutathione cycle and levels of ascorbate and glutathione in the cAPX-S1 were not changed. We found that the cytosolic APX suppression significantly influences the response to various environmental stress conditions in the transformant cell lines.
