ABSTRACT
Reactive oxygen species (ROS) play a central role in plant defense. Superoxide anion, hydrogen peroxide and hydroxyl are the three major forms of ROS. ROS are potentially toxic, and their overproduction as a result of the responses of the plants to biotic/abiotic stress causes an imbalance in the cell’s redox state commonly that may lead to cell death. ROS thus formed can function as cellular second messengers that are likely to modulate many different proteins, leading to a variety of responses. There are many diverse opinions on ROS-induced signaling. According to some, the signaling is specific, but others oppose this notion. ROS themselves are the most likely signals of oxidative stress. The ROS-interacting gene network of plants includes all the genes that encode not only ROS-detoxifying but also ROS-producing proteins in the cell. The dynamic and rapid nature of ROS signaling in cells is an outcome of two opposite processes, that is ROS production and scavenging.
