Pathogenesis-related proteins

Pathogenesis-Related Proteins (PR proteins) are a group of proteins that are induced in plants in response to pathogen invasion or environmental stress. They are part of the plant's innate immune system, and their production is one of the many changes that occur in plants during infection or stress.

Classification

PR proteins are classified into 17 families, PR-1 to PR-17, based on their amino acid sequence, biological activity, and other properties. Each family has distinct characteristics and functions. For example, PR-1 proteins are markers for systemic acquired resistance (SAR), a type of plant immune response, while PR-5 proteins have antifungal activity.

Function

The exact function of many PR proteins is still unknown, but they are believed to play a role in inhibiting pathogen growth and/or signaling other defense responses in the plant. Some PR proteins have antimicrobial activity, while others may function in signaling or other aspects of the plant defense response. For example, PR-1 proteins are thought to have antimicrobial activity, while PR-2 proteins (β-1,3-glucanases) and PR-3 proteins (chitinases) can degrade the cell walls of fungi.

Induction

PR proteins are induced by various signals, including salicylic acid, a plant hormone that is often produced in response to pathogen invasion. Other signals that can induce PR proteins include jasmonic acid, ethylene, and certain types of pathogen-associated molecular patterns (PAMPs).

Role in Plant Defense

PR proteins are an important part of the plant's defense against pathogens. They are produced in response to pathogen invasion and can inhibit the growth of the pathogen, signal other defense responses, and/or help to repair damage caused by the pathogen. In addition, the production of PR proteins is often associated with systemic acquired resistance (SAR), a type of plant immune response that provides long-lasting, broad-spectrum resistance to a variety of pathogens.

See Also

• Systemic acquired resistance
• Plant defense against herbivory
• Plant pathology
• Plant hormone