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

Growth regulators

Auxins

Cytokinins

Gibberellins

Abscisic acid

Ethylene

Brassinosteroids

All are small

organics: made in

one part, affect

another part


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!

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


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

  • 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!


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

  • 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


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

Cytokinins

Discovered as factors which induce cultured cells to divide

Haberlandt (1913): phloem chemical stimulates division

van Overbeek (1941): coconut milk stimulates division


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

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!


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

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


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

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


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

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


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

Cytokinins

Requires auxin to stimulate division

Kinetin/auxin determines tissue formed (original fig)


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

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


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

Cytokinins

Miller& Letham (1961) ± simultaneously found zeatin

Later found in many spp including coconut milk

Kinetintrans-Zeatin


Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

  • 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


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    Cytokinins

    Many other natural & synthetics have been identified

    Like auxins, many are bound to sugars or nucleotides


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    Cytokinins

    Many other natural & synthetics have been identified

    Like auxins, many are bound to sugars or nucleotides

    Inactive, but easily converted


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Synthesis

      Most cytokinins are made at root

      apical meristem & transported to

      sinks in xylem


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Synthesis

      Most cytokinins are made at root

      apical meristem & transported to

      sinks in xylem

      Therefore have inverse gradient

      with IAA


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

      Regulate cell division

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


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

      Regulate cell division

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

  • SAM & plants are smaller when

    [CK]


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

  • SAM & plants are smaller when [CK]

  • Roots are longer!


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

    • Usually roots have too much CK: inhibits division!

    • Cytokinins mainly act @ root & shoot meristems


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    Cytokinin Effects

    Cytokinins mainly act @ root & shoot meristems

    Control G1-> S & G2-> M transition


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

    • Promote lateral bud growth


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

    • Promote lateral bud growth

    • Delay leaf senescence


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Effects

    • Promote lateral bud growth

    • Delay leaf senescence

    • Promote cp development, even in dark


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    Cytokinin Receptors

    Receptors were identified by mutation

    Resemble bacterial 2-component signaling systems


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Action

      1.Cytokinin binds receptor's extracellular domain


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Action

      1.Cytokinin binds receptor's extracellular domain

      2. Activated protein kinases His kinase & receiver domains


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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)


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Action

      4. AHP-P enters nucleus &

      kinases ARR response

      regulators

      5. Type B ARR induce type A


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Cytokinin Action

      4. AHP-P enters nucleus &

      kinases ARR response

      regulators

      5. Type B ARR induce type A

      6. Type A create cytokinin

      responses


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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.


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • Discovered by studying "foolish seedling" disease in rice

    • Hori (1898): caused by a fungus


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • Discovered by studying "foolish seedling" disease in rice

    • Hori (1898): caused by a fungus

    • Sawada (1912): growth is caused by fungal stimulus


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • Discovered in plants in 1950s

    • "rescued" some dwarf corn & pea mutants


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • Discovered in plants in 1950s

    • "rescued" some dwarf corn & pea mutants

    • Made rosette plants bolt


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • Discovered in plants in 1950s

    • "rescued" some dwarf corn & pea mutants

    • Made rosette plants bolt

    • Trigger adulthood in

    • ivy & conifers


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • "rescued" some dwarf corn & pea mutants

    • Made rosette plants bolt

    • Trigger adulthood in ivy & conifers

    • Induce growth

    • of seedless fruit


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

    • "rescued" some dwarf corn & pea mutants

    • Made rosette plants bolt

    • Trigger adulthood in ivy & conifers

    • Induce growth of seedless fruit

    • Promote seed germination


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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)!


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

  • >136 gibberellins (based on

  • structure)!

  • Most plants have >10


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

  • >136 gibberellins (based on

  • structure)!

  • Most plants have >10

  • Activity varies dramatically!


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

  • >136 gibberellins (based on

  • structure)!

  • Most plants have >10

  • Activity varies dramatically!

  • Most are precursors or

  • degradation products


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    Gibberellin signaling

    Used mutants to learn about GA signaling


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellin signaling

    • Used mutants to learn about GA signaling

    • Many are involved in GA synthesis


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellin signaling

    • Used mutants to learn about GA signaling

    • Many are involved in GA synthesis

      • Varies during development


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • Gibberellins

  • GAs 1, 3 & 4 are most bioactive

  • Act by triggering degradation

  • of DELLA repressors


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    • 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)


  • Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    Gibberellins & barley germination

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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    GA & stem elongation

    GA increase elongation, but lag >>> IAA


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    GA & stem elongation

    GA increase elongation, but lag >>> IAA

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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    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


    Growth regulators auxins cytokinins gibberellins abscisic acid ethylene brassinosteroids all are small organics made in one part affect another part

    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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