Week 12 Flashcards
What is a compatible interaction?
Plant susceptible, pathogen virulent (disease develops)
What is an incompatible interaction?
Plant resistant, pathogen avirulent (no disease develops)
What is the PAMP-Triggered immunity also called?
Basal resistance
What is the effector triggered susceptibility also called?
race-specific susceptibility
What is the effector triggered immunity also called?
race-specific resistance
What is the first step in evolution of plant defences?
PAMP-resistance which the causes a selective pressure for pathogens to resist PAMP triggered immunity
How does the pathogen supress PAMP-Triggered immunity?
Effector Triggered susceptibility causing a selective pressure in plants
How do plants respond to pathogen effectors?
The plants detect the presence of effectors through R proteins in the process of ETI
What does PAMPs stand for?
Pathogen associated molecular patterns
What is special abouts PAMPs?
They are conserved pathogen molecules eg bacterial flagellin or fungal chitin
What is FLS2?
Flagellin sensing 2 is a transmembrane receptor kinase that binds to a 22 amino acid peptide from flagellin
What is FLS2 made up from?
1173 amino acid protein has a extracellular domain with 28 leucine rich repeats (LRRs) and a intracellular protein kinase domain
What happens if a plant is a fls2 mutant?
They exhibit enhanced susceptibility to bacterial pathogens such as Pseudomonas syringae
What forms the bacterial Type III secretion system?
It is formed through Hrp proteins. Several Hrp proteins form a pilus through which effectors are translocated
What impact does effectors have on bacterial virulence?
Effectors have a virulence function as knocking one out can decrease the number of bacteria infecting a plant
What is the function of the effector AvrPtoB?
AvrPtoB causes degradation of FLS2, suggesting that supression of FLS2 is the virulence function of AvrPtoB
What are avirulence (Avr) proteins?
They are effectors that the plants recognise
What is the guard model for ETI?
The same as indirect binding of pathogen effectors
What is required for Cf-2 mediated resistance?
It requires the cysteine protease Rcr3
What is the model defence with Cf-2?
Cf-2 monitors state of Rcr3 and activated defence if Rcr3 is inhibited by Avr2
What is the function of Avr2?
It is a cysteine protease inhibitor
What is Cf-2?
It is a transmembrane R protein
What happens when R-Avr interaction occurs?
It intiates signalling, including synthesis of reactive oxygen species that leads to programmed cell death
What is the hypersensitive response of plants?
Programmed death of plant cells. Hypersensitive response deprives obligate pathogens of the living cells they require
What happens to genes when R-Avr interaction occurs?
R-Avr interaction initiates signalling that leads to altered gene expression
What is the pathway for R-Avr altered gene expression?
Leads to the production of salicylic acid (main substance in Aspyrin)
What does salicylic acid signals?
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
