Plant non-canonical peptides: From identification to mechanisms.

Plant peptides have emerged as key regulators of plant growth, development, immunity, and environmental adaptation. Early studies in crops demonstrate the potential application of certain peptides, such as systemin and plant elicitor peptides, to enhance disease resistance. Based on their structure and function, plant peptides are typically classified into canonical peptides, non-canonical peptides, and non-ribosomal peptides. Advances in peptidogenomics and mass spectrometry enable genome-wide discovery of numerous endogenous peptides, including those translated from untranslated regions and non-coding RNAs, greatly expanding the known plant peptidome. This review provides a comprehensive overview of plant peptides, including their classification, biosynthesis, and functional mechanisms in regulating diverse biological processes. Importantly, it systematically summarizes the historical development and recent advances in strategies for plant peptide identification. Despite substantial progress, peptide discovery and functional annotation remain challenging. We therefore propose that integrating high-throughput technologies, functional genomics, and synthetic biology will be essential for unlocking the full potential of plant peptides in crop improvement and cross-disciplinary innovation.