Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play crucial roles in plant defense mechanisms. They act both as signaling molecules and direct agents against pathogen invasion. While ROS and RNS are often linked to oxidative stress, they are essential for the plant immune response. They initiate signal transduction pathways that activate defense genes, strengthen cell walls, and trigger programmed cell death to limit the spread of pathogens. The dual roles of these substances as both stressors and defenders highlight the complexity of their functions in plant biology. This Topical Collection features 14 insightful papers, including nine original research articles, four comprehensive reviews, and one focus article. These contributions enhance our understanding of the roles of ROS and RNS in plant defense. They explore various aspects, from molecular signaling pathways to the interactions between ROS, RNS, and other defense molecules. As global agricultural challenges continue to grow, gaining a deeper understanding of these mechanisms is crucial for developing more resilient crops.
