Recent Research

Peptides function as hormonal agents, transmitting intercellular signals that govern intricate intracellular transcriptional networks during complex developmental processes. In vascular tissues, lignin plays a crucial role in plant terrestrialization, serving functions in water conduction and structural support, and forming physical barriers against pathogen infiltration. While comprehensive knowledge exists regarding the transcriptional networks controlling lignin biosynthesis, the role of long-distance mobile peptides transported through vascular sap in regulating monolignol biosynthesis remains elusive.

In this study, high-throughput peptidomic analyses were employed to uncover a cluster of evolutionarily conserved long-distance migrating peptides present in the vascular sap of six angiosperms: Cinnamomum kanehirae, Populus trichocarpa, Eucalyptus grandis, Glycine max (soybean), Solanum lycopersicum (tomato), and Zea mays (maize). Among these species, we identified a single identical sap peptide, designated as Angiosperm Sap Peptide (ASAP). ASAP demonstrated the ability to reinforce the plant cell wall by enhancing the S-lignin pathway, thereby triggering salicylic acid-mediated immune responses crucial for resisting root-knot nematodes.

Further phosphoproteomic analyses revealed that ASAP rapidly induces protein phosphorylation involved in lignin biosynthesis and xylem development. Sequence identity analysis indicated the emergence of ASAP in land plants, suggesting its evolutionarily conserved role in regulating lignin biosynthesis, facilitating plant terrestrialization, and enhancing resistance against pathogens.