Pathogenesis-related protein

Proteins involved in plant defense mechanisms

Pathogenesis-related proteins (PR proteins) are a group of proteins that are induced in plants in response to pathogen attack. These proteins play a crucial role in the plant's immune system, helping to defend against pathogens such as bacteria, fungi, and viruses. PR proteins are part of the plant's systemic acquired resistance (SAR) and are involved in various defense mechanisms.

Classification

PR proteins are classified into several families based on their structure and function. Some of the major families include:

• PR-1: These proteins are often used as markers for SAR and are involved in antifungal activity.
• PR-2: Also known as beta-1,3-glucanases, these enzymes degrade the cell walls of fungi.
• PR-3: This family includes chitinases, which break down chitin in fungal cell walls.
• PR-4: These proteins have both chitinase and antifungal properties.
• PR-5: Also known as thaumatin-like proteins, they exhibit antifungal activity.

Function

PR proteins are involved in various defense responses, including:

• Direct antimicrobial activity: Many PR proteins have enzymatic activities that degrade pathogen cell walls or inhibit their growth.
• Signaling: Some PR proteins are involved in signaling pathways that activate other defense responses.
• Strengthening of plant cell walls: By modifying the plant cell wall, PR proteins can make it more difficult for pathogens to penetrate.

Induction

PR proteins are typically induced by:

• Pathogen attack: The presence of a pathogen can trigger the expression of PR proteins.
• Environmental stress: Conditions such as drought or extreme temperatures can also lead to the induction of PR proteins.
• Chemical signals: Compounds like salicylic acid and jasmonic acid are known to induce PR protein expression.

Role in Systemic Acquired Resistance

Systemic acquired resistance

Systemic acquired resistance (SAR) is a "whole-plant" resistance response that provides long-lasting protection against a broad spectrum of pathogens. PR proteins are key components of SAR, and their expression is often used as a marker for this type of resistance. SAR is typically activated by a localized infection, leading to the expression of PR proteins throughout the plant.

Applications in Agriculture

Understanding and manipulating PR proteins can have significant implications for agriculture. By enhancing the expression of PR proteins, crops can be made more resistant to diseases, reducing the need for chemical pesticides and increasing yield.

Related pages

• Plant immune system
• Systemic acquired resistance
• Chitinase
• Beta-1,3-glucanase