Molecular Mechanisms Underpinning Signaling Function of ROS

ROS are important secondary messengers, which transduce signals to trigger growth, development, and acclimatization or resistance response in plants under various abiotic and biotic stress. ROS-mediated signaling network is a complex process, engaging various components such as mitogen-activated protein kinases (MAPKs), redox-sensitive proteins, transcription factors (TFs), and others. Further, ROS produced in different cellular compartments mediate different signaling pathways and show cross-talk with other signaling molecules such as calcium (Ca2+), reactive nitrogen species (RNS), and phytohormones like abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and ethylene (ET). Cross-talk between ROS signals and other signaling pathways results in either complementary, synergistic or antagonistic effects on regulatory mechanisms. Moreover, ROS function either upstream or downstream of other signaling components to upregulate specific gene expression. The transient increase in ROS under multifarious stress conditions in a particular cellular compartment triggers a specific response by relaying a message to the nucleus via a complex network. Understanding the cellular language of complex ROS signaling networks is therefore crucial and could facilitate future research for reducing the challenge of food scarcity. The accumulated wealth of knowledge will help enhance the perception of the molecular mechanism of ROS signaling in plants.