Full length flagellin from Pseudomonas aeruginosa prolongs the persistence of immune activation than the core flg22 peptide

Flg22, a peptide consisting of 22 amino acids derived from the N-terminus of the flagellin protein, is a well-established pathogen-associated molecular pattern (PAMP) that triggers a range of immune responses in plants. Through comparative analysis of immunological activation induced by flagellin from Pseudomonas aeruginosa and its core sequence, flg22, we have determined that while flg22 is critical for flagellin-mediated immune activation, significant differences exist between the immune responses elicited by full-length flagellin and flg22 alone. Flagellin enhances the persistence of the FLS2 receptor complex on plant cell membranes, thereby extending early immune responses, as evidenced by slower MAPK phosphorylation and the modulation of the initial ethylene burst, resulting in a delayed but overall higher accumulation of ethylene. In contrast to flg22, flagellin prolongs immune activation, leading to more substantial callose deposition and heightened programmed cell death in the later stages of immune response. This extended immune engagement confers greater resistance to pathogen invasion in Arabidopsis thaliana, maize, and rice, thereby offering prolonged immunity. Our findings provide critical insights into the same roles of flagellin and flg22 in plant immune activation to different extents and lay the foundation for future application of flagellin-based biopesticides as a novel strategy for crop disease management.