Crop diseases continue to threaten yield, fruit quality, and sustainable production. Fire blight, caused by Erwinia amylovora, is one of the most damaging diseases of pear and can severely affect orchard productivity. Current control strategies rely largely on resistant cultivars and chemical treatments, but breeding takes time, resistance may be unstable, and pesticide use can raise concerns over food safety, environmental balance, and pathogen resistance. Plant elicitor peptides are endogenous phytocytokines that help plants perceive danger and rapidly activate defense responses. However, whether these peptide signals can function across plant families has remained debated. Due to these challenges, further research is needed to identify safe, plant-derived immune inducers with broader crop-protection potential.
A research team from the Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University, the Zhejiang Key Laboratory of Biology and Ecological Regulation of Crop Pathogens and Insects, and the Hainan Institute, Zhejiang University, reported (DOI: 10.1093/hr/uhag027) the findings in Horticulture Research on January 29, 2026. The study investigated two pear peptides, PbePep4 from Pyrus betulifolia and PdrPep6 from Pyrus ussuriensis × communis Zhongai, and tested their ability to activate immunity in pear as well as in Brassicaceae and Cucurbitaceae crops.
The researchers first identified seven PROPEP precursors and nine plant elicitor peptide receptors (PEPRs) from multiple pear varieties. They then tested whether PbePep4 and PdrPep6 could protect pear leaves against fire blight. Pretreatment with either peptide significantly reduced disease symptoms and pathogen accumulation after E. amylovora infection. The peptides did not directly suppress bacterial growth, showing that the protection came from immune activation rather than antimicrobial toxicity. In pear tissues, both peptides triggered reactive oxygen species (ROS) production, hydrogen peroxide accumulation, callose deposition, mitogen-activated protein kinase (MAPK) phosphorylation, and increased expression of defense-related genes, including FRK1 and WRKY33. The team then moved beyond pear. PbePep4 and PdrPep6 activated immune responses in Arabidopsis thaliana, Brassica napus, cabbage, watermelon, and pumpkin. They also enhanced resistance to Sclerotinia sclerotiorum in A. thaliana and oilseed rape and to Botrytis cinerea in watermelon. By contrast, the peptides did not induce comparable ROS responses in tomato, tobacco, chili, rice, or maize, indicating selective rather than universal cross-family activity.
The authors said the work helps clarify whether plant elicitor peptides are limited to immune signaling within their family of origin. Their results show that at least some pear peptides can cross family boundaries and activate conserved defense machinery in selected crops. They said this capacity is linked to similarity in the conserved C-terminal motif of plant elicitor peptides (Peps) and to key binding sites in PEPR proteins. In particular, six amino acid residues in PbePEPR1a contributed to peptide perception, offering a molecular explanation for why Rosaceae, Brassicaceae, and Cucurbitaceae plants responded while Solanaceae and Poaceae species did not.
The findings point to a new strategy for disease control: using plant-derived peptides to prime immunity before severe infection develops. Because PbePep4 and PdrPep6 improved resistance in pear, oilseed rape, A. thaliana, and watermelon, they may serve as candidate broad-spectrum immune inducers across selected crop groups. Such peptides could complement resistant breeding and help reduce reliance on conventional pesticides, especially against necrotrophic pathogens. Before field application, further work will be needed to define optimal dosage, treatment timing, formulation stability, and crop-specific performance under agricultural conditions. The study also opens possibilities for molecular breeding or engineering approaches that improve peptide perception and expand the practical use of endogenous immune signals in sustainable crop protection.
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References
DOI
10.1093/hr/uhag027
Original Source URL
https://doi.org/10.1093/hr/uhag027
Funding information
This work was financially supported by grants from the National Key R&D program of China (2021YFD1400200), the Hainan Provincial Natural Science Foundation of China (324CXTD430), and Zhejiang Provincial Natural Science Foundation of China (LZYQ25C140001).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.