Baker Plant signalling

Question 1

How does plant development differ from animals?

Answer 1

No cell migration,

Meristem tissue retains ability to differentiate

Question 2

How do plants adapt to environment?

Answer 2

biochemically and physically

Question 3

What are the 4 types of meristem?

Answer 3

shoot apical
auxillary
lateral
root apical

Question 4

What are the main targets of signalling?

Answer 4

transcription factors, enzymes and cytoskeleton

Question 5

What structure are plant hormones?

Answer 5

aromatic/conjugated small organics or peptides

Question 6

What cell properties are affected by signalling?

Answer 6

Spatial differentiation of tissues, cells and within organs
polarity
growth rates

Question 7

Where are hormones produced?

Answer 7

all cells

Question 8

Where do plant hormones act?

Answer 8

On their own/different cells with a pleiotropic effect

Question 9

How are plant hormones regulated?

Answer 9

locally-no CNS

Question 10

What are the classic hormones?

Answer 10

Auxins
Cytokinins
gibberellins
absisic acid
ethylene

Question 11

What are jasmonates involved in?

Answer 11

carbon partitionning
mechanotransduction
senescence 
reproductive development 
stress resposes

Question 12

How do jasmonates respond to biotic stress?

Answer 12

upregulate production of protease inhibitors to deter herbivore
produce volatile compounds to attract parastiods and prime adjacent plants

Question 13

What is an example of a volatile compound produced in response to biotic stress?

Answer 13

meJA

Question 14

How are Jasmonates produced?

Answer 14

alpha linoleic acid release by phospholipases
13-(S)-HPOT by 13-lipoxogenase
allene oxide by AOS
cis-(+)-OPDA by AOC
export into peroxisome
activartion by OPR3
3 Beta oxidation
export to cytoplasm
conjugation

Question 15

Where are jasmonates released from the membrane?

Answer 15

chloroplast

Question 16

What are the JA animal cell analogs?

Answer 16

prostaglandins

Question 17

How are JA stored?

Answer 17

Conjugation to amino acids or methylation

Question 18

Which amino acid is JA mostly conjugated to?

Answer 18

isoleucine

Question 19

What are modified JAs known as?

Answer 19

oxylipins

Question 20

How is JA imported into the peroxisome?

Answer 20

Mostly by ABC transporter but some ion trapping

Question 21

Which ABC transporter imports JA?

Answer 21

Class D comatose

Question 22

Which compound mimicks JA-Ile?

Answer 22

coronatine bacterial toxin

Question 23

What are the biosynthesis mutants for JA?

Answer 23

Orp3 (OPDA activation)
Fadd triple mutant (no alpha-linoleic acid)
cts1/2 import mutants

Question 24

What characteristics do JA mutants have?

Answer 24

male sterility and increased susceptibility to disease

Question 25

Which type of JA mutant is reversible?

Answer 25

biosynthesis

Question 26

What is the JA response mutant?

Answer 26

coi1

Question 27

What does coi1 encode?

Answer 27

SCF F box specificity of E3 ubiquitin ligase

Question 28

What is the mechanism of JA activation?

Answer 28

JA-Ile acts as SCFcoi1 F box binds JAZ (repressor) to promote E3 ubiquitination genes are expressed

Question 29

What characteristics do coi1 mutants have?

Answer 29

male sterility, increases susceptibility to disease resistance to bacterial toxins and MeJA

Question 30

What do the auxin family control?

Answer 30

``` tropic growth, apical dominance organogenesis pattern formation polarity ```

Question 31

How are auxins produced?

Answer 31

Derived mostly from tryptophan in a series of interlinked pathways under development and environmental control

Question 32

Which enzymes are involved in synthesising auxins?

Answer 32

Aminotransferases, decarboxylases and oxidases

Question 33

What is the main natural auxin?

Answer 33

indole-3-acetic acid

Question 34

Why are synthetic auxins used?

Answer 34

More stable

Question 35

How are auxins stored?

Answer 35

Conjugated through an ester bond to sugars

Question 36

How are auxins transported?

Answer 36

Through phloem for fast, non polar transport | Through cells using carrier proteins for polarity

Question 37

Which proteins transport auxins?

Answer 37

AUX1 influx, PIN efflux | PGP4 influx, PGP1 efflux

Question 38

How does AUX1 transport auxins?

Answer 38

As ions with H+ down a concentration gradient from pH5.5 to pH7

Question 39

How do plant cells maintain the H+ gradient?

Answer 39

P class ATPase

Question 40

Where are PINs found in respect to AUX1?

Answer 40

opposite site of cell

Question 41

What is the positionning of PINs in a root tip?

Answer 41

PIN1 and 4 bring auxins down centre PIN3/7 act as quiescent centre PIN2 transports up edge cells

Question 42

Is PIN distribution constant?

Answer 42

No, changes during development and in response to environment

Question 43

How is PIN expression controlled?

Answer 43

Synthesis in ER and transported in vesicles to plasma membrane. Clathrin mediated endocytosis consitutively recycles Degraded in the vacuole

Question 44

What determines location of PINs?

Answer 44

phosphorylation

Question 45

How is endocytosis stopped?

Answer 45

high [auxin]

Question 46

How are gravity tropisms produced?

Answer 46

Gravity detected by statolit starch granules. PIN3 redistributes from all over cell to basal membrane and cells change shape/ grow assymetrically to restore vertical

Question 47

How does auxin cause gene expression?

Answer 47

Binds aux/IAA repressor as the SCF-TIR1 F box unit of ubiquitin ligase. Repressor degraded and ARF promoter activated

Question 48

How many mutants with no auxin have been discovered?

Answer 48

None