Plant Defences

• How do plants respond to attacks by pathogens?

  Plants actively respond to attack by pathogens
• What are some examples of passive physical defences in plants?

  Waxy cuticle, bark, cellulose cell walls, callose
• What are the two main types of plant defences against pathogens?

  • Physical Defences
  • Chemical Defences
• What is the role of callose in plant defence?

  Callose acts like polyfilla, plugging holes and damaged areas around infected cells
• What happens to callose after a pathogen attacks a plant?

  Callose seals the infected cell off from surrounding healthy cells
• How does lignin contribute to plant defence?

  Lignin thickens and strengthens the barrier created by callose
• What is the effect of callose on sieve plates in the phloem?

  Callose seals off sieve plates, preventing the spread of pathogens
• What types of chemicals do plants produce when attacked by pathogens?

  Plants produce powerful chemicals such as insect repellents, insecticides, antibacterials, and antifungals
• What is an example of an insect repellent produced by plants?

  Pine resin is an example of an insect repellent
• What do chitinases do in plant defence?

  Chitinases break down cell walls of fungi
• What is necrosis in plants?

  Necrosis is deliberate cell suicide to save the rest of the plant
• What is the purpose of stomatal closure in plants?

  Stomatal closure prevents pathogen entry when detected
• What is tylose formation in plants?

  Tylose formation is a balloon-like swelling that fills the xylem vessel
• How do phenols contribute to plant defence?

  Phenols act as antibiotics and antifungals, inhibiting insect attacks
• What are defensins in plant defence?

  Defensins are small proteins with broad antimicrobial action
• What type of compounds are alkaloids?

  Alkaloids are nitrogen-containing compounds
• How do terpenoids function in plant defence?

  Terpenoids have antibacterial and antifungal properties
• What are the differences between passive and active chemical defences in plants?

  Passive Chemical Defences:

  • Present before infection
  • Require less energy

  
  

  Active Chemical Defences:

  • Produced after infection is detected
  • Require more energy
• What are the key components of physical defences in plants?

  1. Cellulose cell walls
  2. Lignin thickening
  3. Waxy cuticle
  4. Stomatal closure
  5. Tylose formation
  6. Callose deposition
• What are the key components of chemical defences in plants?

  1. Defensins
  2. Alkaloids
  3. Phenols
  4. Hydrolytic enzymes
  5. Terpenoids