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Growth regulators Auxins Cytokinins Gibberellins Abscisic acid Ethylene Brassinosteroids All are small organics: made in one part, affect another part

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Growth regulators Auxins Cytokinins Gibberellins Abscisic acid Ethylene Brassinosteroids All are small organics: made - PowerPoint PPT Presentation


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Growth regulators Auxins Cytokinins Gibberellins Abscisic acid Ethylene Brassinosteroids All are small organics: made in one part, affect another part. Auxin signaling Auxin receptors eg TIR1 are E3 ubiquitin ligases !

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Presentation Transcript
slide1

Growth regulators

Auxins

Cytokinins

Gibberellins

Abscisic acid

Ethylene

Brassinosteroids

All are small

organics: made in

one part, affect

another part

slide2

Auxin signaling

Auxin receptors eg TIR1 are E3 ubiquitin ligases!

Upon binding auxin they activate complexes targeting AUX/IAA proteins for degradation!

AUX/IAA inhibit ARF

transcription factors,

so this turns on

"early genes"

Some early genes turn on

\'late genes" needed for

development

slide3

Auxin signaling

  • ABP1 is a different IAA receptor localized in ER
  • Activates PM H+ pump by sending it to PM & keeping it there
  • Does not affect gene expression!
slide4

Auxin & other growth regulators

  • Some "late genes" synthesize ethylene (normally a wounding response): how 2,4-D kills?
  • Auxin/cytokinin determines
  • whether callus forms roots or shoots
slide5

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

slide6

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

van Overbeek (1941): coconut milk stimulates division

slide7

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

van Overbeek (1941): coconut milk stimulates division

Miller… Skoog (1955): degraded DNA stimulates division!

slide8

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

van Overbeek (1941): coconut milk stimulates division

Miller… Skoog (1955): degraded DNA stimulates division!

Kinetin was the breakdown product

slide9

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

van Overbeek (1941): coconut milk stimulates division

Miller… Skoog (1955): degraded DNA stimulates division!

Kinetin was the breakdown product

Derived from adenine

slide10

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

van Overbeek (1941): coconut milk stimulates division

Miller… Skoog (1955): degraded DNA stimulates division!

Kinetin was the breakdown product

Derived from adenine

Requires auxin to stimulate division

slide11

Cytokinins

Requires auxin to stimulate division

Kinetin/auxin determines tissue formed (original fig)

slide12

Cytokinins

Requires auxin to stimulate division

Kinetin/auxin determines tissue formed

Inspired search for natural cytokinins

Miller& Letham (1961) ± simultaneously found zeatin in corn

Kinetintrans- Zeatin

slide13

Cytokinins

Miller& Letham (1961) ± simultaneously found zeatin

Later found in many spp including coconut milk

Kinetintrans-Zeatin

slide14

Cytokinins

  • Miller& Letham (1961) ±
  • simultaneously found zeatin
  • Later found in many spp
  • including coconut milk
  • Trans form is more active,
  • but both exist (& work)
  • Many other natural &
  • synthetics have been identified
slide15

Cytokinins

Many other natural & synthetics have been identified

Like auxins, many are bound to sugars or nucleotides

slide16

Cytokinins

Many other natural & synthetics have been identified

Like auxins, many are bound to sugars or nucleotides

Inactive, but easily converted

slide17

Cytokinin Synthesis

Most cytokinins are made at root

apical meristem & transported to

sinks in xylem

slide18

Cytokinin Synthesis

Most cytokinins are made at root

apical meristem & transported to

sinks in xylem

Therefore have inverse gradient

with IAA

slide19

Cytokinin Synthesis

Most cytokinins are made at root

apical meristem & transported to

sinks in xylem

Therefore have inverse gradient

with IAA

Why IAA/CK affects

development

slide20

Cytokinin Synthesis

Most cytokinins are made at root

apical meristem & transported to

sinks in xylem

Therefore have inverse gradient

with IAA

Why IAA/CK affects development

Rapidly metabolized by sink

slide21

Cytokinin Effects

Regulate cell division

  • Need mutants defective in CK metabolism or signaling to detect this in vivo
slide22

Cytokinin Effects

Regulate cell division

  • Need mutants defective in CK metabolism or signaling to detect this in vivo
  • SAM & plants are smaller when

[CK]

slide23

Cytokinin Effects

  • SAM & plants are smaller when [CK]
  • Roots are longer!
slide24

Cytokinin Effects

  • Usually roots have too much CK: inhibits division!
  • Cytokinins mainly act @ root & shoot meristems
slide25

Cytokinin Effects

Cytokinins mainly act @ root & shoot meristems

Control G1-> S & G2-> M transition

slide26

Cytokinin Effects

  • Promote lateral bud growth
slide27

Cytokinin Effects

  • Promote lateral bud growth
  • Delay leaf senescence
slide28

Cytokinin Effects

  • Promote lateral bud growth
  • Delay leaf senescence
  • Promote cp development, even in dark
slide29

Cytokinin Receptors

Receptors were identified by mutation

Resemble bacterial 2-component signaling systems

slide30

Cytokinin Action

1.Cytokinin binds receptor\'s extracellular domain

slide31

Cytokinin Action

1.Cytokinin binds receptor\'s extracellular domain

2. Activated protein kinases His kinase & receiver domains

slide32

Cytokinin Action

1.Cytokinin binds receptor\'s extracellular domain

2. Activated protein kinases His kinase & receiver domains

3. Receiver kinases His-P transfer relay protein (AHP)

slide33

Cytokinin Action

1.Cytokinin binds receptor\'s extracellular domain

2. Activated protein kinases His kinase & receiver domains

3. Receiver kinases His-P transfer

relay protein (AHP)

4. AHP-P enters nucleus &

kinases ARR response regulators

slide34

Cytokinin Action

4. AHP-P enters nucleus &

kinases ARR response

regulators

5. Type B ARR induce type A

slide35

Cytokinin Action

4. AHP-P enters nucleus &

kinases ARR response

regulators

5. Type B ARR induce type A

6. Type A create cytokinin

responses

slide36

Cytokinin Action

4. AHP-P enters nucleus &

kinases ARR response

regulators

5. Type B ARR induce type A

6. Type A create cytokinin

responses

7. Most other effectors are unknown

but D cyclins is one effect.

slide37

Auxin & other growth regulators

  • Some "late genes" synthesize ethylene (normally a wounding response): how 2,4-D kills?
  • Auxin/cytokinin determines whether callus forms roots or shoots
  • Auxin induces Gibberellins
slide38

Gibberellins

  • Discovered by studying "foolish seedling" disease in rice
  • Hori (1898): caused by a fungus
slide39

Gibberellins

  • Discovered by studying "foolish seedling" disease in rice
  • Hori (1898): caused by a fungus
  • Sawada (1912): growth is caused by fungal stimulus
slide40

Gibberellins

  • Discovered by studying "foolish seedling" disease in rice
  • Hori (1898): caused by a fungus
  • Sawada (1912): growth is caused by fungal stimulus
  • Kurosawa (1926): fungal filtrate causes these effects
slide41

Gibberellins

  • Discovered by studying "foolish seedling" disease in rice
  • Kurosawa (1926): fungal filtrate causes these effects
  • Yabuta (1935): purified gibberellins from filtrates of
  • Gibberellafujikuroi cultures
slide42

Gibberellins

  • Discovered by studying "foolish seedling" disease in rice
  • Kurosawa (1926): fungal filtrate causes these effects
  • Yabuta (1935): purified gibberellins from filtrates of
  • Gibberellafujikuroi cultures
  • Discovered in
  • plants in 1950s
slide43

Gibberellins

  • Discovered in plants in 1950s
  • "rescued" some dwarf corn & pea mutants
slide44

Gibberellins

  • Discovered in plants in 1950s
  • "rescued" some dwarf corn & pea mutants
  • Made rosette plants bolt
slide45

Gibberellins

  • Discovered in plants in 1950s
  • "rescued" some dwarf corn & pea mutants
  • Made rosette plants bolt
  • Trigger adulthood in
  • ivy & conifers
slide46

Gibberellins

  • "rescued" some dwarf corn & pea mutants
  • Made rosette plants bolt
  • Trigger adulthood in ivy & conifers
  • Induce growth
  • of seedless fruit
slide47

Gibberellins

  • "rescued" some dwarf corn & pea mutants
  • Made rosette plants bolt
  • Trigger adulthood in ivy & conifers
  • Induce growth of seedless fruit
  • Promote seed germination
slide48

Gibberellins

  • "rescued" some dwarf corn & pea mutants
  • Made rosette plants bolt
  • Trigger adulthood in ivy & conifers
  • Induce growth of seedless fruit
  • Promote seed germination
  • Inhibitors shorten stems: prevent lodging
slide49

Gibberellins

  • "rescued" some dwarf corn
  • & pea mutants
  • Made rosette plants bolt
  • Trigger adulthood in ivy
  • & conifers
  • Induce growth of seedless fruit
  • Promote seed germination
  • Inhibitors shorten stems:
  • prevent lodging
  • >136 gibberellins (based on
  • structure)!
slide50

Gibberellins

  • >136 gibberellins (based on
  • structure)!
  • Most plants have >10
slide51

Gibberellins

  • >136 gibberellins (based on
  • structure)!
  • Most plants have >10
  • Activity varies dramatically!
slide52

Gibberellins

  • >136 gibberellins (based on
  • structure)!
  • Most plants have >10
  • Activity varies dramatically!
  • Most are precursors or
  • degradation products
slide53

Gibberellins

  • >136 gibberellins (based on
  • structure)!
  • Most plants have >10
  • Activity varies dramatically!
  • Most are precursors or
  • degradation products
  • GAs 1, 3 & 4 are most bioactive
slide54

Gibberellin signaling

Used mutants to learn about GA signaling

slide55

Gibberellin signaling

  • Used mutants to learn about GA signaling
  • Many are involved in GA synthesis
slide56

Gibberellin signaling

  • Used mutants to learn about GA signaling
  • Many are involved in GA synthesis
    • Varies during development
slide57

Gibberellin signaling

  • Used mutants to learn about GA signaling
  • Many are involved in GA synthesis
    • Varies during development
  • Others hit GA signaling
    • Gid = GA insensitive
slide58

Gibberellin signaling

  • Used mutants to learn about GA signaling
  • Many are involved in GA synthesis
    • Varies during development
  • Others hit GA signaling
    • Gid = GA insensitive
    • encode GA receptors
slide59

Gibberellin signaling

  • Used mutants to learn about GA signaling
  • Many are involved in GA synthesis
    • Varies during development
  • Others hit GA signaling
    • Gid = GA insensitive
    • encode GA receptors
    • Sly = E3 receptors
slide60

Gibberellin signaling

  • Used mutants to learn about GA signaling
  • Many are involved in GA synthesis
    • Varies during development
  • Others hit GA signaling
    • Gid = GA insensitive
    • encode GA receptors
    • Sly = E3 receptors
    • DELLA (eg rga) =
    • repressors of GA signaling
slide61

Gibberellins

  • GAs 1, 3 & 4 are most bioactive
  • Act by triggering degradation
  • of DELLA repressors
slide62

Gibberellins

  • GAs 1, 3 & 4 are most bioactive
  • Made at many locations in plant
  • Act by triggering degradation
  • of DELLA repressors
  • w/o GA DELLA binds & blocks activator (GRAS)
slide63

Gibberellins

Act by triggering degradation of DELLA repressors

w/o GA DELLA binds & blocks activator

bioactive GA binds GID1; GA-GID1 binds DELLA & marks for destruction

slide64

Gibberellins

Act by triggering degradation of DELLA repressors

w/o GA DELLA binds & blocks activator

bioactive GA binds GID1; GA-GID1 binds DELLA & marks for destruction

GA early genes are

transcribed, start

GA responses

slide65

Gibberellins & barley germination

GA made by embryo diffuse to aleurone & trigger events leading to germination

slide66

GA & stem elongation

GA increase elongation, but lag >>> IAA

slide67

GA & stem elongation

GA increase elongation, but lag >>> IAA

Increase cell wall creepage, but don\'t change pH (much)

slide68

GA & stem elongation

GA increase elongation, but lag >>> IAA

Increase cell wall creepage, but don\'t change pH (much)

Part of effect is increased

expansin gene expression

slide69

GA & stem elongation

GA increase elongation, but lag >>> IAA

Increase cell wall creepage, but don\'t change pH (much)

Part of effect is increased

expansin gene expression

Another part is increased

cell division

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