985298.fig.005
Figure 5: Model explaining the perception of enhanced ROS involving redox components or antioxidant system. Under normal growing condition (I), ROS are produced as a consequence of many metabolic events and are efficiently removed by detox-scavenging of antioxidants. However, under stress (II), increased production of ROS or oxidative burst causes increased oxidation of “sensor-scavenging” redox components locked into signal transduction pathways. Signaling pathway operates via kinase cascades and other secondary messengers that ultimately lead to upregulation of ROS detoxification capacity (acclamatory pathway) or cell death pathway involving defense withdrawal. The decisive factors that determine the feasibility of acclamatory pathway or cell death pathway are yet to found out but could involve the intensity of oxidative stress or ROS signal and their location.