Peptide Hormone Signaling in Photoprotection

Peptide hormones have emerged as critical regulators of plant development and environmental stress responses. Unlike classical phytohormones, these small, secreted peptides exert precise control over cell-to-cell communication through receptor-like kinases (RLKs). In recent years, their involvement in abiotic stress responses—especially light-induced stress—has gained increasing attention. Simultaneously, photoprotection mechanisms safeguard photosynthesis under excess light by dissipating excess energy and scavenging reactive oxygen species (ROS). This review integrates the current understanding of peptide hormone biosynthesis, posttranslational modifications, and receptor-mediated signaling with their roles in modulating photosynthesis and photoprotection. Key peptide families, including CLE, RALF, PSK, and IDA, are shown to regulate ROS homeostasis, transcriptional networks, and hormonal cross talk, contributing to systemic acclimation and enhanced photosynthetic performance under stress. The intersection of peptide signaling with antioxidant systems, chloroplast–nucleus communication, and transcription factor regulation suggests new opportunities for crop improvement. Advances in genetic engineering and synthetic peptide application provide a promising route to increase resilience in crops exposed to fluctuating light and climate conditions.