Plant Genetics Disease Resistance

Question 1

What are some common pathogens of plants?

Answer 1

• Fungi
• Bacteria
• Viruses.

Question 2

What are some common pests of plants?

Answer 2

• Nematodes
• Insects
• Vertebrates.

Question 3

What is the difference between complete and partial resistance?

Answer 3

Complete resistance (vertical resistance) is very specific to one pathogen whereas partial resistance (horizontal resistance) is not specific and targets a range of pathogens.

Question 4

What are the two different disease resistance mechanisms in plants?

Answer 4

Partial and complete resistance.

Question 5

What is the gene-for-gene theory of complete resistance?

Answer 5

If the pathogen has an Avirulence gene and the host a Resistance gene, then there is no infection.

Question 6

What is an Avirulence gene?

Answer 6

It codes for an Elicitor molecule or protein controlling the synthesis of an elicitor. It is dominant.

Question 7

What is a resistance gene?

Answer 7

The Resistance gene codes for a receptor molecule which ‘recognises’ the Elicitor. It is dominant.

Question 8

What is an elicitor?

Answer 8

• Elicitors are proteins made by the pathogen avirulence genes, or the products of those proteins.
• It is a molecule which induces any plant defence response.

Question 9

What does a resistance gene code for?

Answer 9

The receptor for the specific elicitor associated with the interacting avirulence gene.