Hydrogen peroxide, nitric oxide and cytosolic ascorbate peroxidase at the crossroad between defence and cell death

An increase in the production of ROS is a typical event occurring during different stress conditions and activating conflicting rseponses in plants. In order to investigate teh relevance of different timing and amounts of ROS production, tobacco Bright Yellow-2 cells were incubated with different amount of glucose plus glucose oxidase, for generating H2O2 during time, or directly with known amounts of H2O2. Time of ROS production is critical because it can detrmine programmed cell death or necrosis. Depending on the different kind of activated cell death, ascorbate and glutathione pools are altered differently. Ascorbate peroxidase has been anlysed under different H2O2 generations. The chamnges in ASC, GSH, and APX are involved in the signalling pathway leading to PCD, probably contributing to guaranteeiing the cellular redox conditons required for successful PCD.