How do plants respond to pathogen attacks?

Plants respond to pathogen attacks by activating their immune system, producing defensive chemicals and sometimes closing their stomata.

Plants have a complex immune system that helps them to defend against pathogen attacks. When a pathogen invades a plant, the plant's cells recognise the foreign organism and trigger a response. This response involves the production of defensive chemicals that can kill the pathogen or slow its growth. Some of these chemicals also act as signals to other parts of the plant, alerting them to the presence of the pathogen and preparing them for potential attack.

One of the key defensive chemicals produced by plants is salicylic acid. This molecule is involved in local and systemic plant defence responses against pathogens. It helps to strengthen the cell walls of the plant, making it more difficult for the pathogen to penetrate. Salicylic acid also promotes the production of pathogenesis-related proteins, which can directly attack the pathogen.

In addition to producing defensive chemicals, plants can also physically respond to pathogen attacks. For example, they may close their stomata (the small openings on the surface of leaves that allow for gas exchange) to prevent the pathogen from entering. Some plants can also form a cork layer at the site of infection to isolate and prevent the spread of the pathogen.

Furthermore, plants have a unique ability to 'remember' a pathogen attack. This is known as systemic acquired resistance (SAR). After an initial infection, the plant becomes resistant to future infections by the same or similar pathogens. This is achieved through the production of 'memory' cells that can recognise the pathogen and trigger a faster and stronger immune response.

In summary, plants have a variety of strategies to defend against pathogen attacks. These include the production of defensive chemicals, physical responses such as closing their stomata, and the ability to 'remember' past infections to provide future protection.