This special issue, edited by Jean-Pierre Jacquot and Mirko Zaffagnini, focuses on the thioredoxin and glutaredoxin systems, which are crucial for redox regulation in various organisms. The issue includes 16 papers, 12 of which report experimental research data, and 4 review-like articles. The content covers a wide range of topics, including the roles of these systems in plant physiology, redox regulation in bacteria, and their involvement in stress responses and protein function. Key topics include the physiological roles of methionine sulfoxide reductases, the structure and function of thioredoxin and glutaredoxin enzymes, and the impact of these systems on developmental processes and stress responses. The issue also highlights the use of fluorescent biosensors to study the dynamics of reactive oxygen species (ROS) and their signaling pathways. Overall, the special issue provides valuable insights into the complex mechanisms of redox regulation and the importance of these systems in maintaining cellular homeostasis.This special issue, edited by Jean-Pierre Jacquot and Mirko Zaffagnini, focuses on the thioredoxin and glutaredoxin systems, which are crucial for redox regulation in various organisms. The issue includes 16 papers, 12 of which report experimental research data, and 4 review-like articles. The content covers a wide range of topics, including the roles of these systems in plant physiology, redox regulation in bacteria, and their involvement in stress responses and protein function. Key topics include the physiological roles of methionine sulfoxide reductases, the structure and function of thioredoxin and glutaredoxin enzymes, and the impact of these systems on developmental processes and stress responses. The issue also highlights the use of fluorescent biosensors to study the dynamics of reactive oxygen species (ROS) and their signaling pathways. Overall, the special issue provides valuable insights into the complex mechanisms of redox regulation and the importance of these systems in maintaining cellular homeostasis.