The power of small signaling peptides in crop and horticultural plants

Small signaling peptides, generally comprising fewer than 100 amino acids, act as crucial signaling molecules in cell-to-cell communications. Upon perception by their membrane-localized corresponding receptors or co-receptors, these peptide-receptor modules then (de)activate either long-distance or local signaling pathways, thereby orchestrating developmental and adaptive responses via (post)transcriptional, (post)translational, and epigenetic regulations. The physiological functions of small signaling peptides are implicated in a multitude of developmental processes and adaptive responses, including but not limited to, shoot and root morphogenesis, organ abscission, nodulation, Casparian strip formation, pollen development, taproot growth, and various abiotic stress responses such as aluminum, cadmium, drought, cold, and salinity. Additionally, they play a critical role in response to pathogenic invasions. These small signaling peptides also modulate significant agronomic and horticultural traits, such as fruit size, maize kernel development, fiber elongation, and rice awn formation. Here, we underscore the roles of several small signaling peptide families such as CLE, RALF, EPFL, miPEP, CEP, IDA/IDL, and PSK in regulating these biological processes. These novel insights will deepen our current understanding of small signaling peptides, and offer innovative strategies for genetic breeding stress-tolerant crops and horticultural plants, contributing to establish sustainable agricultural systems.