plant defences

• Physical barriers:

  • A thick cellulose cell wall, which is impermeable to many pathogens

  • A thick waxy cuticle on the surface of the leaf, which acts as a barrier to most pathogens

  • Leaves can often close their stomata to stop pathogens entering the plant.
• Chemical barriers:

  • Cells of some plants can produce antimicrobial chemicals, proteins and enzymes

  • Some plants can release compounds that attract larger insects than the pests, which feed on the pests and stop them eating the plant.