bacteria (lecture 2)

Question 1

how do bacteria overcome plants innate IR

Answer 1

they secrete effectors

Question 2

type 3 secretion system?

Answer 2

pumps proteins (effectors) from bacteria cytoplasm into plant cytoplasm.
secreted by the pilus.

Question 3

genes for type 3 secretion system?

Answer 3

hrp genes now known as hrc. organised in clusters.

Question 4

what happens when bacteria comes into contact with plant cell wall?

Answer 4

(all) bacteria have the same response elicited. cell wall - PrhA protein - hrp genes - pip box - more hrp genes - pilus formation (type 3 secretion mech)

Question 5

what is pathogenicity dependent on?

Answer 5

all bacteria have type 3 secretion system formed. but what causes pathogenicity in some species is the effectors that are secreted from the pilus.

Question 6

avirulence genes and effectors?

Answer 6

about 30 effectors some are detected by plant resistance genes some are not. the ones that are are avirulent.
detection:
avrBS1 - res gene BS1
effectors interact with proteins in the plants cytoplasm and are then transported to the nucleus where they act like a cysteine protease. Destroy proteins involved in the innate IR.

Question 7

overview?

Answer 7

Avr gene - hrp pilus - effectors into plant cytoplasm - importin takes to nucleus - protease activity.

Question 8

type 1 and 2 secretion system?

Answer 8

cell wall degrading enzymes. e.g. proteases. produced in plant cytoplasm and pumped into extracellular space. driven ATP hydrolysis (atp pump).