Amino acid vectorization of salicylic acid enables efficient activation of NPR1 ‐dependent defense without phytotoxicity

This study highlights SA-amino acid conjugates as effective, non-phytotoxic inducers of plant immunity. Structure-activity analyses indicate that both the nature of the SA-amino acid linkage and the properties of the amino acid side chain modulate biological activity, induction kinetics, and toxicity. Conjugates 3a and 7a combine strong protective efficacy with the absence of SA-associated phytotoxicity, supporting amino acid vectorization as an effective approach for safer and controlled SA delivery and the rational design of next-generation defense stimulators for sustainable crop protection.