Plant Hormone Signal transduction pathway 05/26/2006

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Plant Hormone Signal transduction
pathway05/26/2006

• by Men-Chi, Chang
• ???
• Assistant Professor
• Department of Agronomy
• National Taiwan university
• menchi_at_ntu.edu.tw

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Talk Outline

• General introduction to cell signaling
  transduction pathways in plant.
• Different plant hormones and their physiological
  function in plants.
• Comparison between plant hormones and animal
  hormones.
• Ways or approaches in studying plant hormone
• signaling transduction pathways.
• Molecular mechanism of various plant hormone
  signal transduction pathways
• (a) ubiquitin-dependent protein degradation
• (negative regulator)
• (b) tow component system (phospho-relay).

6. Manipulation of plant growth and
development with knowledge from plant
hormone signal transduction pathway.
ex. Second green revolution.
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Cell Signaling transduction pathway
CPU (Central Processing Unit) Chip Signal
Transduction Network Compiling,
Integration, processing
Input (command) Keyboard Signal perception Endoge
nous phytohormone Exogenous environmental cue
Output (performance) Printer Signal
Response Morphogenesis change, Growth
development differentiation
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Various signaling transduction pathways in plants
Calcium (Ca2) signaling (regulatory
network) Lipid signaling transduction
pathway Reactive oxygen species (ROS) signaling
Nitric oxide (NO) signaling transduction
pathway Sugar sensing responsive
pathway Wounding-signal transduction pathway
(plant-pathogen interaction) Light signaling
responsive pathway Biological oclock (circadian
rhythm) regulatory pathway
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Development regulatory pathway e. g. flowering
(autonomous), lead, root, trichome formation
root apical meristem (RAM) shoot
apical meristem (SAM) formation polarity
and cell cytoskeleton rearrangement Specific
cell fate determination and differentiation (Xylem
and phloem specification, root organization
(patterning)) Abiotic stress signaling
pathways (salt, drought, heat, cold, metal,
vernalization etc.) Plant hormone signaling
transduction (auxin, ethylene, cytokinin,
gibberellin, abscisic acid, brasinosteroid,
jasmonic acid etc.)
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Definition of plant hormone

• The word hormone is derived from the Greek verb
  meaning to excite.
• hormones are organic substances synthesized in
  one tissue and transported out where their
  presence results in physiological responses ( not
  always true may act at or close to synthesis
  site). They are required in minute amounts (10-6
  to 10 -8M).
• 3. Each hormone may result in multiple effects --
  the particular effect depending on a number of
  factors
• (a) the presence of other hormones and the
  presence of activator molecules ( calcium,
  sugars)
• (b) the amount of the hormone (dosage or
  concentration)
• (c) the sensitivity of that tissue to the
  hormone.
• (d) the condition of the plant itself is
  critical what is the condition of the plant? its
  age?

Site of action x developmental stage x
concentration of hormone? Crosstalk and
specificity?
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Chemical Structures of the Plant Hormones
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Effects of plant hormones on plant growth and
development
Senescence

• Embryogenesis

(Cell division, expansion, differentiation and
cell death)
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What is the difference between plant hormones and
animal hormones?
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Top-down and bottom-up approaches to study
biological problems
Systematic biology (Breeding or Genetics
approach Top-down Data-driven)
Phenotype Environment (G x E effect) Metabolite
s Protein (modification) Genes
interaction (genome background, network) gene
Transgenic approach (bottom-up,
hypothesis-driven Molecular biology)
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Plant hormone signaling transduction

• Auxin
• TIR1 F-box protein (Ubiquitin conjugated
  ligase)
• PIN1 (pin-formed 1)
• Aux/IAA repressor
• Ethylene
• histidine kinase
• Raf-like kinase CTR1
• Mitogen activated protein kinase cascade
• Cytokinin
• phosphorelay (two-component system)
• 4. Gibberellin
• G protein and DELLA protein
• hexosamine (NAcGlu)
• 5. Abscisic acid
• PP2C protein
• Farnesylation
• Brasinosteroid
• BRI1 (LRR-RLK)

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Comparison between auxin and gibberellin
signaling pathway
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Phenotypes associated with the auxin and
gibberellin receptor mutants.
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Composition of the transmembrane phytohormone
receptors
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Brassinosteroid signaling pathway
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Phenotypes associated with the brassinosteroid,
ethylene, cytokinin and abscisic acid
receptor mutants
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Ethylene and cytokininsignaling pathways (two
component system)
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The abscisic acid (ABA) signaling pathway that
controls the regulation of flowering time
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Major transcription factors and cis-regulatory
elements involved in abscisic acid
ABA-dependent stress responses
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Genetic manipulation of GAmetabolism or signal
transduction pathway? (second Green Revolution?)
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Thanks for your attention!
Thanks for your attention!
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