BRIEF RESEARCH REPORT article
Front. Plant Sci.
Sec. Plant Pathogen Interactions
This article is part of the Research TopicDecoding Receptor-Mediated Recognition: Comparative Study of PRR and NLR Functions in Host Resistance to Plant PathogensView all articles
Discovery that PACAP, a Mammalian Neuropeptide, Activates Plant Immunity through Chemical Screening
Provisionally accepted
- Nanjing Forestry University, Nanjing, China
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Plants are constantly exposed to a variety of biotic stresses in their natural environment and rely on their immune systems to adapt to these challenges. Pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) constitute two complementary layers of the plant innate immune system, both of which can be activated by immune elicitors. In this study, a pFRK1-GUS reporter system was employed to screen multiple natural product libraries, leading to the identification of the animal-derived neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) and its truncated form, PACAP 6–38, as potential plant immune elicitors. Exogenous application of PACAP and PACAP 6–38 triggered multiple PTI-associated immune responses, including cytosolic calcium influx, MAPK phosphorylation, and induction of FRK1 expression under the tested conditions, while notably failing to induce a detectable reactive oxygen species (ROS) burst. Moreover, pre-treatment with PACAP or PACAP 6–38 at the tested concentrations reduced bacterial titers of Pseudomonas syringae pv. tomato DC3000 by approximately 0.3–0.7 log units under single-application conditions. Notably, both peptides also enhanced plant resistance to Ralstonia solanacearum, indicating a broader role in bacterial disease resistance. Although the molecular receptors and downstream signaling components remain to be identified, this study establishes a proof-of-concept for cross-kingdom recognition of an animal neuropeptide by plants. Together, these findings highlight PACAP-induced immunity as being uncoupled from the canonical ROS burst, underscoring the conceptual novelty of animal-derived peptides as unconventional elicitors and providing a reference for potential future applications of PACAP in plants.
Keywords: Disease Resistance, Neuropeptide, peptide, plant immune inducer, Plant Innate Immunity (PTI)
Received: 14 Jan 2026; Accepted: 29 Jan 2026.
Copyright: © 2026 Dong, Ye, Xu, Zhou and He. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Kunrong He
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