Abiotic stress signal transduction pathway in plants --- a case study for chilling and freezing tolerance - PowerPoint PPT Presentation

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Abiotic stress signal transduction pathway in plants --- a case study for chilling and freezing tolerance

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Title: Abiotic stress signal transduction pathway in plants --- a case study for chilling and freezing tolerance


1
Abiotic stress signal transduction pathway in
plants--- a case study for chilling and freezing
tolerance
by Men-Chi, Chang (???) Assistant Professor,
Department of Agronomy National Taiwan
University menchi _at_ ntu.edu.tw, May 18th, 2007
2
Talk Outline
  • Introduction.
  • Global weather change and crop production.
  • Mechanism of cold /freezing tolerance in plants
  • (CBF regulon).
  • 3. Molecular genetic analysis of cold tolerance
    mechanism.
  • (Luminance bio-image screening cos, los, hos
    mutants).
  • 4. Current transformation approaches in
    generation freezing/ or chilling tolerance
    plants.

3
Sustainability of crop production and food
security will that still be true tomorrow?
  • Today
  • 2 billion people lack reliable access to food.
  • 800 million people today are chronically
    malnourished.
  • (300 million of these are children)

4
Average yields and record yields of eight major
crops
Average loses (kg/Ha) Average loses (kg/Ha) Abiotic loses/ record of yield
Crop Record yield (kg/Ha) Average yield (kg/Ha) Biotic stresses Abiotic stresses
Corn 19300 4600 1952 12700 65.8
Wheat 14500 1880 726 11900 82.1
Soybean 7390 1610 666 5120 69.3
Sorghum 20100 2830 1051 16200 80.6
Oat 10600 1720 924 7690 75.1
Barley 11400 2050 765 8590 75.4
Potato 94100 28300 17775 50900 54.1
Sugar beat 121000 42600 17100 61300 50.7
(Buchanan et al.,2000)
5
  • Why study abiotic stress tolerance in in plants?
  • Abiotic stresses, such as high or low
    temperature, drought and
  • salinity are most important factors that limit
    the geographical
  • distributions of plants on earth.
  • 2. Abiotic stresses usually cause severe loss of
    crop yields.
  • 3. Abiotc stresses affect global crop production
    system and
  • endanger food security of human being.

6
Morphological and physiological changes of
Plants under temperature stress
Morphology block germination, reduced water
absorption of root, wilted and chlorosis
leaves, delay heading and ripening,
sterility. Physiology change membrane
fluidity, reduce photosynthesis,
inhibit/enhance respiration, reduce ATP/ADP
energy charge, disturbed osmotic balance, slow
down de novo protein synthesis, cause
oxidative stress.
7
Cold acclimation induces changes of many genes
in various cellular processes of plants
(Xin and Brose,2000)
8
The complexity of the plant responses to
different abiotic stresses
Wangxia Wang et al., (2003)
9
Proposed events occurred in plants under low
Temperature treatment
Cold-activated transcriptional cascade in
Arabidopsis
Temperature decline below 15?
Membrane Fluidity changes
Genotype- Independent events
Calcium wave
IP3
Protein Kinase/Phosphatase cascade
Induction or repression of TFs expression
Genotype- Dependent events
Cold-specific genes response
DRE/CRT, A/GCCGAC ABRE, PyACGTGGC MYB,
C/TAACNA MYC, CANNTG
Development of freezing tolerance
10
Scientists who contribute in the cold signal
transduction pathway studies in plants
11
Cold signaling pathway Multiple signaling
pathways and probably multiple temperature
sensors are used in high plants to initiate and
control cold acclimation. COR pathway ESK /or
other CRT/DRE-regulon (CBF regulon) esk1
(Eskimo) -ABA-dependent sfr (sensitive to -ABA
independent freezing) (quite conserve
between ada2 (transcriptional monocot and dicot
plants) factor) In Arabidopsis, only 12 of the
cold-responsive genes actually belongs to the CBF
regulon.
12
Isolation and functional analysis of CBF genes
by yeast one-hybrid analysis
P.N.A.S 941035-1040 (1997)
13
The Plant Journal 16(4) 433 -442 (1998)
14
Changes in CBF transcript levels in response to
low temperature
The Plant Journal 16(4) 433 -442 (1998)
15
Screening for sfr (sensitive to freezing
resistance) mutants
Plant Physiology 111 1011-1019 (1996)
16
Luminance bioimage screening of mutants involved
in abiotic stress signal transduction pathway
PRD29ALUC bioluminescent genetic screen
The Plant Cell 9, 1935 1949 (1997)
17
The Protocol Used for the Screening for Mutants
The Plant Cell 9, 1935 1949 (1997)
18
Seedling morphology
(before) cold and ABA treatment
Osmotic stress
ABA treatment
Cold 2 days
(after)
The Plant Cell 9, 1935 1949 (1997)
19
H/LOS high/Low expression of osmotically
responsive genes COS constitutive expression of
osmotically responsive genes
The Plant Cell 9, 1935 1949 (1997)
20
  • HOS 1 RING finger protein (E3 ligase)
  • HOS 9 Homeodomain transcriptional factor
  • HOS 10 R2R3 MYB factor
  • LOS1 translational elongation factor 2
  • LOS2 bi-functional nolase
  • LOS4 DEAD-box RNA helicase
  • LOS5 Moco surfurase

21
ICE1 (inducer of CBF expression 1), an upstream
transcription factor that regulates the
transcription of CBF genes in the cold
PCBF3LUC bioluminescent genetic screen
Genes and Development 17 1043-1054 (2003)
22
Cold sensing and secondary signals
  • Cold stress-induced rigidification of the plasma
  • membrane at microdomains may lead to actin
  • cytoskeletal rearrangement, which may be
  • followed by activation of Ca2 channels and
  • increased cytosolic Ca2 level, triggering the
  • expression of COR genes during cold acclimation.

23
AFs in 3-day-old BY-2 cells maintained at 0oC for
012 h. Rhodamin-phalloidin staining
Plant, Cell and Environment (2004) 27 , 641653
24
Is Microtubule Disassembly a Trigger for Cold
Acclimation?
Plant, Cell and Environment (2004) 27 , 641653
25
Cold-activation of BN115 and regulation by
modulators of membrane fluidity
The Plant Journal (2001) 27(1), 1-12
26
Proposed events occurred in plants under low
Temperature treatment
Cold-activated transcriptional cascade in
Arabidopsis
Temperature decline below 15?
Membrane Fluidity changes
Genotype- Independent events
Calcium wave
IP3
Protein Kinase/Phosphatase cascade
Induction or repression of TFs expression
Genotype- Dependent events
Cold-specific genes response
DRE/CRT, A/GCCGAC ABRE, PyACGTGGC MYB,
C/TAACNA MYC, CANNTG
Development of freezing tolerance
27
Analysis of low-temperature effects on the
regulation of metabolic pathways in Arabidopsis
using the BIOPATHAT tool
P.N.A.S 101(42) 14996-14997 (2004)
28
Current transformation approaches in generation
freezing/ or chilling tolerance plants
  1. Biosynthetic enzymes for osmoprotectants (i.e.
    mannitol, proline, trehalose or glycine betaine).
  2. Expression of stress-induced proteins (such as
    LEA, HSPs).
  3. Altering the enzyme activity of antioxidants
    (such as SOD, GST).
  4. Plasma membrane-associated phospholipase D.
  5. Expression of the transcriptional factors (such
    as CBF1, CBF3 ).
  6. Expression of the intermediates in the
    cold-signaling transduction pathway or oxidative
    stress signaling pathway (such as OsCDPK, MAPK
    etc.)

29
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30
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