13.9 - Plant Defences
Physical plant defences
- Plants don't have an immune system of specialised cells and antibodies like animals do.
- Instead, they use physical defences - barriers that stop pathogens getting into the plant in the first place.
The two physical barriers
- Waxy cuticle - A tough layer covering most leaves and stems. It blocks pathogens from entering, and stops water collecting on the leaf - which lowers the risk of infection by pathogens carried in water.
- Cellulose cell wall - Every plant cell is surrounded by a cell wall made of cellulose, sitting beneath the cuticle. It forms a further barrier against any pathogen that gets past the cuticle.
