This invention discloses the application of PACAP peptides as
plant immunomodulators, belonging to the field of
plant immunology technology. This invention is the first to apply PACAP to a
plant system, discovering that it can act as a novel plant immunomodulator to regulate plant immune responses, thereby enhancing plant resistance to pathogenic microorganisms. Experimental results show that PACAP can rapidly induce
intracellular calcium ion influx in
Arabidopsis thaliana cells, activate the
MAPK signaling pathway, and upregulate the expression of early immune marker genes such as FRK1. Furthermore, PACAP treatment significantly improves plant resistance to pathogens such as *
Pseudomonas syringae* and *
Ralstonia solanacearum*. This invention also confirms that not only does the full-length PACAP (1-38) possess plant immune-promoting activity, but its N-terminal truncated
peptide (1-27) and
receptor antagonist fragment (6-38) also have plant immune-inducing functions. This invention provides a new technical solution for the development of plant immune inducers.