Detecting The Non Self

Question 1

How can plants detect a microbe?

Answer 1

They can detect part of the microbe

Exp.: Chitin which is a component of the cell wall in fungi

Question 2

What are MAMPs?

Answer 2

Microbe - associated molecular patterns

Question 3

What are PAMPS

Answer 3

Pathogen assosiated molecular patterns

Question 4

PRR

Answer 4

Pattern recognition receptors

Sentries on the lookout for microbes inside plant cells

Question 5

What happens when a PRR recognizes a PAMP?

Answer 5

-triggers an influx of Ca2+ ions into the cell -> production of reactive oxygen species (ROS)

The signalling pathway gets activated -> genes responsible for defence get activated

Question 6

What is ROS

Answer 6

Reactive oxygen species

They are antimicrobial and can act as secondary signals

Question 7

What happens in the first phase of the defence gene expression?

Answer 7

• occurs within twenty minutes
  -dependant on ROS production
  -is responsible for producing proteins involves in regulation and signalling defence

Question 8

What happens in the second phase of the defence gene expression?

Answer 8

• dependant on ROS accumilation
• produces enzymes responsible for synthesizing defence components (defensive weapons and further signaling molecules)

Question 9

What is PTI

Answer 9

PAMP triggered immunity -> The two phases of immune response

Question 10

What are effectors?

Answer 10

Molecules created by microbes that are a counter - defensive strategy

Question 11

What are effectors able to do?

Answer 11

• block the initial recognition of PAMPs
• be transferred into the cell where they suppress the activation of plant defences

Question 12

What are R Proteins?

Answer 12

Specific proteins that recognize effectors an prevent them from doing their job

ETI

Question 13

What is ETI?

Answer 13

Effector triggered immunity

Is done by r proteins and leads to a rapid activation of very effective plant defences including suicide of the cell under attack

Question 14

What does the r Protein recognize

Answer 14

Pathogen effectors are modifying the plants defensive response. R proteins recognize these changes, not the effector itself -> an exception is the tomato plant, where a r Protein bind directly to the effector

Question 15

What does a flagellum do ?

Answer 15

Its a whip like structure which can propel the bacterium towards attractants

Question 16

What is a lipopolysaccharide flagellin?

Answer 16

A PAMP recognized by receptors on the cell surfaces of mammals and plants

Question 17

How does P.aeruginosa (lung infection causing bacteria) avoid flagellin recognition?

Answer 17

These bacteria are able to degrade any flagellin that is not part of the flagellum -> this hides the bacterium from the immune systems of mammalian and plant hosts.

Question 18

How does P. Syringae overcome plant defences?

Answer 18

It enters the leaf via open stomata -> because the plant closes these, the bacterium produces a toxin called coronatine which reopens the stomata

Question 19

How did Cladosporium fulvum (leaf mold) overcome the SRR in tomato plants?

Answer 19

The SRR recognizes Chitin, so the fungus has adapted to this by producing a protein that binds chitin.

Question 20

What problem does occur because MAMPS are widespread among microbes?

Answer 20

Beneficial microbes and pathogens possess similar MAMPS - beneficial microbes are able to suppress the plants defences

Question 21

What is rhizobium bacteria?

Answer 21

It forms a symbiotic realtionship with leguminous plants

-nodules are formes at the root

-it fixates nitrogen

Question 22

How is Rhizobia recognized within the cell?

Answer 22

• first they are detcted as a thread
• some rhizobia species produce flagellin molecules that dont trigger plant defences
  -Rhizobia can also supress the plants defence responses