Transcript (drought and salt) stresses H 2 O

Advances in Plant Stress #6
Topic in water stress regulation in plant
Diameter of the Earth = 13,000 km
(ice)
Mainly used
this only 0.01%
(Earth water globe)
(rivers)
(salt water)
(fresh water)
(ground water)
(soil water)
From 「みずものがたり」(Mizu-monogatari, in Japanese)
(lakes)
Water stress
• Global shortage of available water and
drought
• Osmotic aspect of salinity stress
• Molecular mechanism of water
transport: Aquaporins
You can download this presentation (pptx-file) from the site:
http://www.rib.okayama-u.ac.jp/MolecularPhysiology/katsuhara/katu_e.html
Global water crises
Water demand
and use form
http://www.unep.org/dewa/vitalwater/article43.html
Global water crises
•
•
•
•
Increase of population
and social
development
Shortage of water for
life and agriculture
Water pollution (Less
quality)
Population in flood
area
In this issue, it was
mentioned that
“10% reduction of
irrigation water saves
water more than all
other uses”
Scientific American
August, 2008
Canal for agriculture
Shrink of Aral Sea
(Central Asia)
60 Km
朝日放送（テレビ朝日系）2008年3月9日放送
http://kobajun.chips.jp/wp-content/uploads/022702.jpg
Even Without a Drought, We’re
Depleting Groundwater at an
Alarming Pace
Map: The Shrinking Ogallala Aquifer
http://modernfarmer.com/2015/07/o
gallala-aquifer-depletion/
No more ground water until 2050
http://www.circleofblue.org/waternews/2014/wo
rld/map-shrinking-ogallala-aquifer-1950-2011/
Over 1 billion people live in areas where groundwater is
disappearing faster than it can be replenished.
http://inhabitat.com/new-study-finds-groundwater-demand-outstrips-supply-for-over-1-billion-people/
California Drought
http://sanfrancisco.cbslocal.com/pho
to-galleries/2015/04/09/californiadrought-2015/
http://www.agweb.com/blog/K
now_Your_Market_281/drough
t_concerns_mounting_in_new_
zealand_and_california_/
World Economic Forum
from Global Risk Report (January 15, 2015)
http://www.weforum.org/reports/global-risks-report-2015
By Dr. Richard Errett Smalley (2003）
Novel Prize, Chemistry 1996
A Puzzle for the Planet
Scientific American 312, 62 - 67 (2015)
The world is trying to
improve energy, water and
food supplies individually,
but the challenges need to
be solved in one integrated
manner. That approach
will also benefit the
environment, poverty,
population growth and
disease.
• Plant scientists can contribute to the solution to this global
water crisis and food production via crops requiring less
water.
• 10% reduction of irrigation water saves more than all others
（ Scientific American 2008, previous issue)
Earth science
Social,
economic,
political
science
Environmental
science
Water
Engineering
Plant and agricultural science
Salinity and water stress
Salt-affected land
From “The use of saline waters for crop production” FAO paper 48 (1992)
Dry land
Saline soil
Saline soil distribution overlaps with dry land
Death Valley (USA)
Bad water (saline water)
High evaporation → Drought
↓
Salt remains → Salt stress
Water with high salt
Mineral
Water
Mineral
Na+↑
Water↓
Na+
Water
(Dehydration)
Sanyo Newspaper
Apr. 3, 2011
Tsunamai
• Arid and semi-arid area <dry land>
(high evaporation)
• Coastal area (sea water)
• Underground salt
New South Wales (Australia)
Raising saline ground water
We must manage water use adequately.
Can We Feed the World & Sustain the Planet?
Scientific American 2011
日本語版日経サイエンス ２０１２年３月号
「人口７０億人時代の食糧戦略」
The world must solve three food problems
simultaneously: end hunger, double food
production by 2050, and do both while
drastically reducing agriculture's damage to
the environment.
http://www.nature.com/scientificamerican/journal/v3
05/n5/full/scientificamerican1111-60.html
Can We Feed the World & Sustain the Planet?
Scientific American 2011
日本語版日経サイエンス ２０１２年３月号
「人口７０億人時代の食糧戦略」
Five solutions, pursued together, can
achieve these goals: (1) stop agriculture from
consuming more tropical land, (2) boost the
productivity of farms that have the lowest
yields, (3) raise the efficiency of water and
fertilizer use worldwide, (4) reduce per
capita meat consumption and (5) reduce
waste in food production and distribution.
http://www.nature.com/scientificamerican/journal/v3
05/n5/full/scientificamerican1111-60.html
Approach from Plant Science
Drought/salt tolerance (efficient/less water usage)
Mechanism of water uptake/transport
Salinity stress
Drought stress
Ionic stress
(K+
deficiency／excess
influx)
Osmotic stress
Na+
Aquaporin
Dehydration
Na+ toxicity
Inhibitions of:
photosynthesis
protein synthesis
enzyme activity
<Signal transduction>
Inhibitions of:
water uptake
cell elongation
leaf development
(Cell death)
Ion homeostasis
Na+ extrusion/compartmentation/
K+ reabsorption
Osmotic adjustment
Accumulations of ions/solutes/organic
compounds
Recovery/Adaptation
A schematic summary of the stresses that plants suffer and resultant responses
of plants to detrimental effects for survival under drought and high salinity.
Molecular transport of water transport
・・・ depends on water potential deference
“Water potential” mainly consists in
“concentration” and “presser”
Physical static presser :
「Presser potential」ψp
Physical presser need to
stop swelling（P)
Water molecule
M
Power of Swelling
・・・”osmotic presser”
（proposal to concentration）
⇒ 「Osmotic potentail」ψosm
「Semi-permeable membrane」
minus (osmotic pressure)
Water can pass but solute (M)
cannnot
Why minuis？
ψp＋ψosm＝０ （balance drnamic equation）
ψ1 ψ2
ψ1 ψ2
ψ1 ψ2
P
P
P
ψosm: -0.1 > -0.5
ψp: 0 < 0.4
(MPa)
(MPa)
Water movement
Water moves from high ψw
to low ψw
Water potential ψw = ψosm + ψp
1 MPa ≈ 0.4 mol/litter ≈ 10 atm （気圧）
ψosm -0.1 > -0.5
0 < 0.4
+ ψp
ψ -0.1 = -0.1
(ψ1 = ψ2)
+ ・・・
This is “Turgor” in
plant cells
(View from water potential)
Animal cells
Plant cells
細胞膜 Plasma-membrane 細胞壁 Cell wall
•Inner ψosm = Outer ψosm
•Inner ψw = Outer ψw
•Inner ψosm ≠ Outer ψosm
•Presser at call wall
•Inner ψw = Outer ψw
At low water potential of soil (drought/ salt stress)
Water potential
－ 0 pure water
Soil
Dehydration
soil
Root
Root
ψw
Weak drought/salt stress
Wet
Water potential
Osmotic adjustment
= reduce cellular ψw
= reduce cellular ψosm
= increase osmotic presser
ψw
soil
Root
soil
Root
Strong drought/salt stress
Soil
root
Compatible solute →
(osmtic compounds)
• Increase osmotic presser
• Chaperon activity
• Scavenging activity
Betaines:
tri-methyl amino acids
H3N+-
→ (CH3)3N+-
Proline:
Example;
Tobacco cells
under salt stress
At low water potential of soil (drought/ salt stress)
Water potential
Increase
permeability
－ 0 pure water
Soil
soil
Root
Root
ψw
Weak drought/salt stress
Wet
Water potential
Osmotic adjustment
= reduce cellular ψw
= reduce cellular ψosm
= increase osmotic presser
ψw
soil
Root
Prevent
soil
Root
Strong drought/salt stress
Soil
root
Water uptake（movement/flux）：
Water flux*＝Driving force×water permeability
（*per unit time）
(駆動力）
（水の動きやすさ：透過性）
Driving force:
Water potential difference
（Dam: gravity potential）
In plant, mainly,
Difference of ψosm
Permeability/conductance:
（Dam: opening of gate）
In plant, mainly,
Activity of aquaporins
Water uptake（movement/flux）：
Water potential difference
Water flux*＝Driving force×water permeability
（*per unit time）
(駆動力）
（水の動きやすさ：透過性）
Surface area×Water permeability per unit area
（表面積）
（面積当たりの水透過性）
Aquaporin determins this
•All bacteria, animal and plants
•Membrane proetin with about 300 amino acids
•Two Asn-Pro-Ala motif
Soil water
Symplastic path
Apoplastic path
casparian stripe
(not permeable)
xylem
root
Aquaporins are
required for water
across the membrane
via symplastic path
Water is most abundantly used in cells.
Aquaporin is a water transporter.
→ Aquaporins regulate largest transport.
Regulation by; humiditiy, salt stress, light, temeperature, others
Localization
Gene family: >30 genes
Substrates:
H2O、CO2、H2O2, B・・・）
aquaporin
生体膜
Plasmamembrane (ＰＩＰ）
Tonolast membrane（ＴＩＰ）
Peribacteroid memebrane
or plasamamembrane (NIP)
ER membrane (SIP)
Output; Stress tolerance, growth regulation, Post-harvesting…
Structure in the membrane
Regulatory regions
Intracellular
trafficking
Open/close
Aquaporins ;
1) increase membrane water permeability
2) make it possible to regulate water
permeability
Murata at al. (2000) Nature 407:599
Prof. Peter Agre
Novel prize (Chemistry)
"for the discovery of water
channels" (2003)
Discovery; 1992
Before discovery of aquaporins？
H 2O
液胞膜
Tonoplast
原形質膜（細胞膜）
Plasma-membraene
After all, the message that appeared in textbooks was that water simply diffused
"somehow'' across plants membrane and proteins were not involved in these
processes.
Biophysicists continued to use pore models to explain membrane permeations
without seeking a molecular explanation.
A.R.Schaffner Planta 204:131-139 (1998)
（Biochemical）
（Functional)
Cell water permeability
Abundant protein
that function is
↓
Higher than lipid bilayer unknown
CHIP28
↓
Water channels suggested
PM28
Aquaporin
（Molecular genetics）
Major Intrinsic Protein
(MIP) in eyes
E.Coli glycerol
transporter
（GlpF)
Prof. Peter Agre
Novel prize (Chemistry)
"for the discovery of water
channels"
Molecular structure of an aquaporin
Tameshite-Gatten 2007 May, 9
Plant aquaporins
Aquaporin =
MIP (membrane intrinsic protein)
PIP(plasm-membrane…)
（原形質膜型）
TIP(tonoplast….)
（液胞膜型）
NIP(Nodulin26-like…)
SIP(small …) ER signaling?
XIP(x …)
35 Major Intrinsic Protein in Arabidopsis
13 genes in human, and 1-2 genes in bacteria
XIPs are found in some plants (tomato,
cotton, moss) but functions are not yet
known
Rice aquaporins
NIP
Nodulin 26-like Intrinsic
OsNIP2;2 Protein
OsNIP3;1
OsNIP3;2
OsSIP2;1
OsNIP3;3
SIP
OsSIP1;1
Small basic Intrinsic OsTIP4;3
Protein
OsTIP4;2
OsPIP2;7
OsTIP4;1
TIP
OsTIP3;2
Tonoplast Intrinsic
Protein
OsTIP3;1
0.1
Localization
Stress response
Substrate
H2O2 ［OsZmPIP2;5, HvPIP2;5］
Si(OH)4 /As(OH)4 ［OsNIP2;1］
B(OH)3 ［ AtNIP5;1 ］
PIP
Plasma membrane Intrinsic
Protein
33 genes in rice
（PCP Ishikawa et al. 46：568 (2005)
Why many in plants?
Experimental difficulty
Individual function
Redundancy
Phenotype/mutant?
External (soil) water
variable
Determining cell water permeability
PIP aquaporins
High permeability: maintain cytoplasm
TIP aquaporins
Vacuole
(More than 90% volume)
•Wet
N
•Dry
•Salt stress
細胞質（cytoplasm）
Plasma-mambrane
Cell wall
air N2
Relation to N2-fixation, too
(Tyerman et al.）
Leguminos root cells
Peribacteroid membrane
N2 → NH3
N-fixing bacteria
窒素固定菌
H2O
NOD26
（NIP-type aquaporin）
Aquaporins under osmotic (drought and salt) stresses
Plasma membrane
H2O
吸水低下
aquaporin
Relative growth (%)
脱水
Reduction of
water uptake
120
100
80
Dehydration
60
40
20
0
-20
0
barley
100
200
NaCl (mM)
300
400
Stress・・・dehydration
H2O
Plasma
membrane
aquaporin
P
P
• Short term response
Inactivation via dephosphorylation and
internalization
• Middle term response
Suppression of aquaporin expression
→ Root water permeability reduction
• Long term reaction
Osmotic adjustment to re-establishment
of motive force
Expression of aquaporin again
Trafficking/recycling regulation
Salt stress
↓
H2O2 as signal
↓
Trafficking
Internalization of fluorescence after H2O2
Boursiac et al. Plant J. (2008) 56, 207–218
Chevaliiner et al.
PCP 56:819 (2015)
Salt stress
H2 O
aquaporin
PM
Overexpression
Osmotic
adjustment
Transient
adaptation
over-expression
Katsuhara et al.
Plant Cell Physiol.
(2003)44:1378-1383
Many physiological reactions elated to aquaporins
Low minerals (Carvajal）
aquaporin expression ↓
→ root water permeability ↓
→ shoot growth ↓
Leaf movements (Moshelion）
Day：Aquaporin amount/activity ↑
→ water influx ↑ → Leaf open
Night)：Aquaporin amount/activity↓
→ Dehydration → Leaf close
Opening tulip flower (Azad）
•
•
•
•
Low temp→high temp, then opening
Flower cells (lower part) uptake water
PIPs express constantly
TgPIP2;2 activation by phosphorylation under Low
temp→high temp
Fruit enlargement （Shiratake）
• Initial・・・cell division
• Middle～Later cell elongation by water uptake
TIPs・・・regulation of expression
PIPs・・・constant expression
regulation via phosphorylation
From aquaporin research…
CO2↑
H2O↑
• High quality flowers
and fruits
• Drought/salt tolerant crops
• High water usage crops
• High CO2 fixing plants
(We are investigation some
CO2-permeable aquaporins)