ISR: Induced Systemic Resistance

Induced Systemic Resistance (ISR) is another significant defense mechanism in plants, akin to Systemic Acquired Resistance (SAR). Both ISR and SAR are forms of induced systemic resistance, and they play essential roles in a plant’s ability to defend against pathogens. However, they differ in terms of their activation mechanisms and signaling pathways.

Here’s a detailed explanation of Induced Systemic Resistance (ISR):

1. Initiation and Priming: ISR is triggered when a plant interacts with specific beneficial microorganisms, such as certain rhizobacteria and mycorrhizal fungi. These beneficial organisms colonize the roots or the rhizosphere and prime the plant’s immune system to respond more effectively to potential pathogen attacks.
2. Beneficial Microorganisms: Rhizobacteria, like certain strains of Pseudomonas and Bacillus, and mycorrhizal fungi, are commonly associated with ISR. These microbes release specific compounds or elicitors that induce the plant’s defense responses.
3. Signal Transmission and Defense Activation: Beneficial microorganisms or their products trigger signaling pathways within the plant, leading to the activation of defense mechanisms. Ethylene, jasmonic acid (JA), and other signaling molecules are involved in this process.
4. Induction of Defense-Related Genes: ISR induces the expression of defense-related genes, including those involved in the synthesis of jasmonic acid, ethylene, and pathogenesis-related proteins. These genes enhance the plant’s ability to defend against a broad range of pathogens.
5. Broad-Spectrum Resistance: ISR provides broad-spectrum resistance, protecting the plant against various pathogens, including bacteria, fungi, and nematodes. It can also confer resistance to different pathogen species compared to those that initially triggered the defense response.
6. Enhanced Growth and Stress Tolerance: Besides disease resistance, ISR has been associated with enhanced plant growth, increased root development, and improved stress tolerance, contributing to overall plant health and vigor.
7. Compatibility with Mycorrhizal Associations: ISR can work in concert with mycorrhizal associations, where beneficial mycorrhizal fungi help induce systemic resistance in plants, leading to an enhanced defense response.
8. Sustainable Plant Protection Strategy: ISR is considered a sustainable and eco-friendly strategy for disease management in agriculture, as it reduces the reliance on synthetic pesticides and fertilizers.

Understanding ISR is crucial for developing biocontrol strategies that harness the potential of beneficial microorganisms to enhance plant health and combat plant diseases in an environmentally friendly manner. It is an important tool in integrated pest management and sustainable agricultural practices.

Talk to your OMEX representative today to learn more about how to promote Induced Systemic