Interaction between Ca2+ and ROS signaling in plants

Reactive oxygen species (ROS) are generally produced during the aerobic metabolism and induce various types of physiological functions in the cells. Initially, it is well known that these are highly reactive and cause cellular toxicity in the plants through oxidative damage, but they are also useful companions for various physiological activities of plant life. Other than chloroplast, these ROS are generated in nonphotosynthetic tissues through enzymes such as NADPH oxidases, cell wall peroxidases, and other cell organelles such as peroxisomes and glyoxysomes. These key enzymes produce H2O2 and O2- in the apoplast. Now, the role of ROS is studied as signaling molecules in various physiological processes of plants such as seed germination, root growth, gravitropism, programmed cell death (PCD), plant growth and their development. As we know that calcium ion (Ca2+) is a secondary messenger, which plays an important role in the regulation of physiological and developmental processes in plants. It releases during activation of factors such as biotic and abiotic stresses. One target of ROS signal transduction is to activate the Ca2+-permeable channels in plant membranes where respiratory burst oxidase homologs (RBOH) play a central role in cellular ROS through signaling network. The present chapter highlights the connection between ROS and Ca2+ signaling in plants for the communication between the cells and also its role in signal transmission.