What is the role of lignin in plant defence?

Lignin plays a crucial role in plant defence by providing structural support and resistance against pathogens and pests.

Lignin is a complex organic polymer that is found in the cell walls of many plants, giving them rigidity and strength. This structural support is essential for the plant's defence as it makes it more difficult for pests and pathogens to penetrate the plant's tissues. The physical barrier created by lignin can deter many types of insects and microorganisms, reducing the likelihood of infection.

Moreover, lignin is chemically resistant to degradation, which means it can withstand the enzymes produced by many pathogens that aim to break down the plant's cell walls. This resistance is particularly important in the plant's defence against fungal pathogens, which often secrete enzymes to degrade the plant's tissues.

In addition to providing a physical and chemical barrier, lignin also plays a role in the plant's immune response. When a plant is attacked, it can respond by producing more lignin to reinforce its cell walls. This process, known as lignification, can help to limit the spread of the pathogen within the plant.

Furthermore, some studies suggest that lignin may have antimicrobial properties. Certain types of lignin can produce compounds that are toxic to pathogens, helping to kill them off and protect the plant.

In summary, lignin is a vital component of the plant's defence system. Its role in providing structural support, resistance to degradation, and potential antimicrobial properties all contribute to the plant's ability to withstand attacks from pests and pathogens.