# Natural products for biocontrol of Pseudomonas syringae: mechanisms and applications

## TL;DR

This review explores natural products from plants, animals, and microbes as eco-friendly alternatives to chemical pesticides for controlling the plant pathogen Pseudomonas syringae.

## Contribution

The paper provides a comprehensive overview of the mechanisms and applications of natural products for biocontrol of P. syringae.

## Key findings

- Plant-derived compounds inhibit P. syringae by targeting T3SS and activating plant immune pathways.
- Animal-derived substances like chitosan and propolis disrupt bacterial membranes and stimulate immunity.
- Microbial natural products interfere with quorum sensing and enhance host immunity for disease suppression.

## Abstract

Pseudomonas syringae functions as a model phytopathogen causing numerous crop diseases, resulting in substantial economic losses in global agriculture. Presently, management of P. syringae predominantly depends on chemical pesticides; however, their prolonged application has contributed to escalating resistance and environmental contamination, highlighting urgent requirement for sustainable biological control approaches. In this review, we examine recent advances in the utilization and mechanistic understanding of natural products derived from plants, animals, and microorganisms for the control of P. syringae. Plant-derived compounds—including flavonoids, terpenoids, and alkaloids—inhibit P. syringae infection by targeting the bacterial type III secretion system (T3SS), disrupting cell membrane integrity, promoting reactive oxygen species (ROS) accumulation, and activating plant immune signaling pathways such as salicylic acid (SA) and jasmonic acid (JA) cascades. Animal-derived substances, such as chitosan, propolis, and antimicrobial peptides, primarily exert antibacterial effects through membrane disruption and immune system stimulation. Microbial-derived natural products contribute to synergistic disease suppression by modulating host immunity and interfering with the pathogen’s quorum sensing mechanisms. Evidence indicates that these natural products possess multi-target antimicrobial properties, offering a rich repository of candidate molecules, such as baicalein, lignans, and carvacrol, for the development of eco-friendly antibacterial agents. Future investigations should focus on detailed characterization of these bioactive compounds and their specific disease targets, optimization of extraction methodologies to improve stability and bioavailability, and comprehensive assessment of environmental safety to advance the industrial implementation of sustainable biocontrol strategies