Chemotaxis to plant defense compounds in phytopathogens
Roberta Genova1,2, Ashleigh Holmes3, Mario Cano-Muñoz1
1Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, Granada, Spain.
Plos Pathogens
|May 20, 2026
Summary
Plant pathogens use specialized chemoreceptors to detect plant defense compounds like benzoate derivatives and agmatine derivatives. This chemotaxis guides them to infection sites, aiding in plant disease development.
Area of Science:
- Microbiology
- Plant Pathology
- Biochemistry
Background:
- Plant pathogens exhibit a higher number of chemoreceptors than average bacteria, indicating complex chemotactic abilities.
- The specific signals and functional significance of most phytopathogen chemoreceptors remain largely unknown.
Purpose of the Study:
- To identify the specific signals recognized by three chemoreceptors (PacH, PacI, PacG) in Pectobacterium atrosepticum.
- To elucidate the role of these chemoreceptors in bacterial chemotaxis and virulence towards plants.
Main Methods:
- Ligand-binding assays using purified ligand-binding domains (LBDs) of chemoreceptors.
- Chemotaxis assays in vitro and in planta.
- High-resolution structural analysis of PacG-LBD.
- Genetic analysis involving gene mutations.
Main Results:
- PacH and PacI recognized benzoate derivatives (salicylate, vanillin, p-hydroxybenzoate); PacG recognized agmatine derivatives (agmatine, feruloylagmatine, p-coumaroylagmatine).
- These compounds are plant defense molecules induced upon pathogen attack and accumulate at infection sites.
- Chemotaxis was induced by all recognized compounds except agmatine, which acted antagonistically.
- A pacG mutant exhibited reduced virulence in planta, highlighting its importance.
Conclusions:
- Pectobacterium atrosepticum utilizes chemoreceptors to sense plant defense compounds, guiding bacterial movement to infection sites.
- This chemotaxis strategy allows pathogens to exploit plant defense mechanisms for colonization.
- The findings expand the known range of chemoeffectors for bacteria and suggest conserved mechanisms across other phytopathogens.
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