Systemic acquired resistance

Definition

Systemic acquired resistance (SAR) is a plant's innate immune response that occurs after an initial localized exposure to a pathogen, leading to enhanced resistance throughout the entire plant. This process is triggered by signaling molecules that travel through the plant, resulting in the activation of defense mechanisms that can help protect against future infections. SAR plays a crucial role in how plants respond to viral infections and related diseases, helping to mitigate symptoms and enhance overall plant health.

5 Must Know Facts For Your Next Test

1. Systemic acquired resistance is often characterized by an increase in the expression of pathogenesis-related (PR) proteins that enhance the plant's ability to combat pathogens.
2. The activation of SAR can lead to long-lasting immunity, allowing plants to better fend off subsequent attacks by the same or related pathogens.
3. In many cases, SAR is dependent on salicylic acid signaling pathways, highlighting the interconnected nature of plant immune responses.
4. Plants can also exhibit systemic acquired resistance in response to abiotic stresses, such as heat or drought, showing the versatility of this defense mechanism.
5. Understanding SAR has practical implications for agriculture, as enhancing this response can improve crop resilience and reduce reliance on chemical pesticides.

Review Questions

• How does systemic acquired resistance enhance a plant's ability to fight off viral infections?
  • Systemic acquired resistance enhances a plant's ability to fight off viral infections by triggering a cascade of defensive responses throughout the plant following an initial localized infection. This involves the production of signaling molecules like salicylic acid, which activate genes responsible for synthesizing pathogenesis-related proteins. These proteins strengthen the plant's defenses, making it more resistant to subsequent viral attacks and reducing the severity of disease symptoms.
• Evaluate the role of salicylic acid in the mechanism of systemic acquired resistance in plants.
  • Salicylic acid plays a critical role in systemic acquired resistance by acting as a signaling molecule that activates defense pathways within the plant. When a pathogen is detected, salicylic acid levels increase, leading to the expression of various defense genes and pathogenesis-related proteins. This not only enhances local defenses but also triggers systemic responses that bolster immunity throughout the entire plant, providing long-term protection against future infections.
• Synthesize information on how understanding systemic acquired resistance can impact agricultural practices and pest management strategies.
  • Understanding systemic acquired resistance can significantly influence agricultural practices and pest management strategies by informing approaches that enhance plant resilience against diseases. By leveraging the mechanisms of SAR, such as promoting salicylic acid pathways or utilizing biocontrol agents that trigger this response, farmers can develop crops with improved defenses against pathogens. This can lead to reduced reliance on chemical pesticides, promoting sustainable agriculture and potentially increasing crop yields while minimizing environmental impact.

Related terms

pathogen-associated molecular patterns (PAMPs): Molecules associated with groups of pathogens that are recognized by the plant's immune system, initiating a defense response.

salicylic acid: A signaling molecule involved in the activation of systemic acquired resistance, which helps to trigger defense responses against pathogens.

induced resistance: A broader term that encompasses various defense strategies in plants activated by pathogen exposure, including systemic acquired resistance and others.