Systemic resistance induced by rhizosphere bacteria
L C van Loon1, P A Bakker, C M Pieterse
1Department of Plant Ecology and Evolutionary Biology, Utrecht University, TB Utrecht, The Netherlands. L.C.vanloon@bio.uu.nl
Annual Review of Phytopathology
|March 12, 2004
Summary
Nonpathogenic rhizobacteria trigger induced systemic resistance (ISR) in plants, enhancing defense against pathogens. This natural plant defense mechanism is effective in field conditions for biological control.
Area of Science:
- Plant Pathology
- Microbiology
- Agronomy
Background:
- Nonpathogenic rhizobacteria induce a plant defense response similar to pathogen-induced systemic acquired resistance (SAR).
- Rhizobacteria-mediated induced systemic resistance (ISR) has been observed against various pathogens in diverse plant species.
- Bacterial strains and plant species exhibit variability in ISR induction and expression.
Purpose of the Study:
- To summarize the phenomenon of rhizobacteria-mediated induced systemic resistance (ISR).
- To outline the mechanisms and plant responses involved in ISR.
- To highlight the potential of ISR as a biological control strategy.
Main Methods:
- Review of existing literature on rhizobacteria-induced systemic resistance (ISR).
- Analysis of bacterial determinants (lipopolysaccharides, siderophores, salicylic acid) and plant signaling pathways (SA-dependent, jasmonic acid, ethylene).
- Evaluation of ISR effectiveness in various plant species and under field conditions.
Main Results:
- ISR is induced by nonpathogenic rhizobacteria, providing resistance against fungi, bacteria, and viruses.
- Bacterial determinants like lipopolysaccharides and siderophores, and plant hormones like salicylic acid, jasmonic acid, and ethylene, are involved in ISR.
- Induced resistance responses are accelerated and enhanced upon pathogen challenge, with no consistent host plant alterations.
Conclusions:
- Rhizobacteria-mediated ISR is a significant plant defense mechanism effective against a broad spectrum of pathogens.
- ISR can be mediated through salicylic acid-dependent or independent pathways, involving jasmonic acid and ethylene.
- ISR represents a promising natural mechanism for biological control of plant diseases in agricultural settings.
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