Redox regulation of plant hormone signaling transduction.

Plants need to precisely coordinate growth and development with stress responses under constantly changing environmental conditions, and the interaction between redox signaling and plant hormone signaling is an important regulatory mechanism underlying this balance. Reactive oxygen species (ROS) are not only oxidative metabolic products generated under stress conditions, but also important second messengers that modulate protein functions through oxidative post-translational modifications (oxi-PTMs). Recent studies have shown that ROS can directly regulate plant hormone signaling transduction through oxi-PTMs. By altering the activity, stability, subcellular localization, or protein interactions of hormone receptors, protein kinases, phosphatases, transcription factors, or hormone metabolic enzymes through redox modifications, ROS regulate the biosynthesis and signaling outputs of multiple hormones, including auxin, abscisic acid (ABA), brassinosteroids (BR), jasmonic acid (JA), salicylic acid (SA), ethylene (ET), and cytokinin (CK). In turn, plant hormones can reshape ROS homeostasis by regulating ROS-producing or -scavenging systems, thereby forming complex bidirectional feedback networks. ROS can also act as common signaling nodes among different hormone pathways to integrate plant growth and development with stress responses. This review summarizes the molecular mechanisms by which redox signals regulate plant hormone signaling transduction, with particular emphasis on the roles of protein redox modifications in hormone perception, signal transmission, and multi-hormone interactions, and discusses the potential of exploiting key redox-sensitive sites for precise crop improvement, with the aim of providing a new theoretical basis for understanding plant environmental adaptation and breeding stress-resistant, high-yielding crops.