Week 12

Question 1

What is a compatible interaction?

Answer 1

Plant susceptible, pathogen virulent (disease develops)

Question 2

What is an incompatible interaction?

Answer 2

Plant resistant, pathogen avirulent (no disease develops)

Question 3

What is the PAMP-Triggered immunity also called?

Answer 3

Basal resistance

Question 4

What is the effector triggered susceptibility also called?

Answer 4

race-specific susceptibility

Question 5

What is the effector triggered immunity also called?

Answer 5

race-specific resistance

Question 6

What is the first step in evolution of plant defences?

Answer 6

PAMP-resistance which the causes a selective pressure for pathogens to resist PAMP triggered immunity

Question 7

How does the pathogen supress PAMP-Triggered immunity?

Answer 7

Effector Triggered susceptibility causing a selective pressure in plants

Question 8

How do plants respond to pathogen effectors?

Answer 8

The plants detect the presence of effectors through R proteins in the process of ETI

Question 9

What does PAMPs stand for?

Answer 9

Pathogen associated molecular patterns

Question 10

What is special abouts PAMPs?

Answer 10

They are conserved pathogen molecules eg bacterial flagellin or fungal chitin

Question 11

What is FLS2?

Answer 11

Flagellin sensing 2 is a transmembrane receptor kinase that binds to a 22 amino acid peptide from flagellin

Question 12

What is FLS2 made up from?

Answer 12

1173 amino acid protein has a extracellular domain with 28 leucine rich repeats (LRRs) and a intracellular protein kinase domain

Question 13

What happens if a plant is a fls2 mutant?

Answer 13

They exhibit enhanced susceptibility to bacterial pathogens such as Pseudomonas syringae

Question 14

What forms the bacterial Type III secretion system?

Answer 14

It is formed through Hrp proteins. Several Hrp proteins form a pilus through which effectors are translocated

Question 15

What impact does effectors have on bacterial virulence?

Answer 15

Effectors have a virulence function as knocking one out can decrease the number of bacteria infecting a plant

Question 16

What is the function of the effector AvrPtoB?

Answer 16

AvrPtoB causes degradation of FLS2, suggesting that supression of FLS2 is the virulence function of AvrPtoB

Question 17

What are avirulence (Avr) proteins?

Answer 17

They are effectors that the plants recognise

Question 18

What is the guard model for ETI?

Answer 18

The same as indirect binding of pathogen effectors

Question 19

What is required for Cf-2 mediated resistance?

Answer 19

It requires the cysteine protease Rcr3

Question 20

What is the model defence with Cf-2?

Answer 20

Cf-2 monitors state of Rcr3 and activated defence if Rcr3 is inhibited by Avr2

Question 21

What is the function of Avr2?

Answer 21

It is a cysteine protease inhibitor

Question 22

What is Cf-2?

Answer 22

It is a transmembrane R protein

Question 23

What happens when R-Avr interaction occurs?

Answer 23

It intiates signalling, including synthesis of reactive oxygen species that leads to programmed cell death

Question 24

What is the hypersensitive response of plants?

Answer 24

Programmed death of plant cells. Hypersensitive response deprives obligate pathogens of the living cells they require

Question 25

What happens to genes when R-Avr interaction occurs?

Answer 25

R-Avr interaction initiates signalling that leads to altered gene expression

Question 26

What is the pathway for R-Avr altered gene expression?

Answer 26

Leads to the production of salicylic acid (main substance in Aspyrin)

Question 27

What does salicylic acid signals?

Answer 27

Increased pathogenesis-related (PR) protein gene expression - PR proteins are antimicrobial, including glucanases and chitinases
Increased Phytoalexin biosynthesis gene expression - Phytoalexins are low molecular weight anitmicrobials