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A presentation by ICRISAT scientist Dr Vincent Vadez on a blue sky research initiative
Citation preview
Developing crops with high productivity at high
temperature:
A blue sky research initiative
BSR Team
29 Nov 2013
Maximum temperature in the SAT
Critical Temperature
threshold
0
5
10
15
20
25
30
35
40
45
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maxim
um
T°C
1983-HQ 1992-HQ
2001-HQ 2012-HQ
1983-ISC 1990-ISC
1998-ISC
Headquarter
Sahelian Center
T°C rarely crosses critical limits
0
1
2
3
4
5
6
7
8
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Maxim
um
VP
D Sahelian
Center
Headquarter
Vapor pressure deficit (VPD) in the SAT (VPD reflects T°C and Rel. Humidity %)
Prevalent high VPD
Effect on plant water balance
VPD threshold
The basics – Why aquaporins (AQP) ?
Transpiration response to VPD
Transpiration response to AQP inhibition
AQP gene expression
AQP in the bigger picture - Drought
Modified from Murata et al., 2000.
What are aquaporins??
Membrane transporter for water Passive transport
Terminal drought sensitive
Terminal drought tolerant
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0.50 1.00 1.50 2.00 2.50 3.00 3.50
VPD (kPa)
H77/2 833-2
PRLT-2/89-33
Tra
nsp
irati
on
(g
cm
-2 h
-1)
Kholova et al 2010 – J. Exp. Bot
Transpiration restriction at high VPD
How the story began – Water savings in millet
Water saving
Why such a rapid transpiration response??
Rapid response hydraulic signal
VPD (kPa)
Where is the source of hydraulic limitation??
???
We hypothesized roots could be the source of hydraulic limitation
Is the hydraulic restriction in the roots only ??
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
09:20 09:40 10:00 10:20 10:40 11:00 11:20 11:40 12:00 12:20 12:40 13:00 13:20
Norm
alized
tra
nsp
irati
on
VPD change
Low VPD High VPD
No difference in slope No hydraulic limitation in the leaves
Apoplastic
Pathway
(Structural)
Symplastic
Pathway
(AQP)
Water pathways in the root cylinder
Two pathways have different hydraulic conductance
Hypothesis: Aquaporin control plant water loss ?
????
The basics – Why aquaporins ?
Transpiration response to VPD
Transpiration response to AQP inhibition
AQP gene expression
AQP in the bigger picture - Drought
Terminal drought sensitive
Terminal drought tolerant
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0.50 1.00 1.50 2.00 2.50 3.00 3.50
VPD (kPa)
H77/2 833-2
PRLT-2/89-33
Tra
nsp
irati
on
(g
cm
-2 h
-1)
Kholova et al 2010 – J. Exp. Bot
One QTL mapped for low Tr at high VPD
Transpiration response to VPD in pearl millet: Growth chamber
M322
M394
M214
M321 M592 M443 M356
M738
40 cM
0
0.005
0.01
0.015
0.02
0.025
0.03
1 2 3 4 5 6 7 8Tra
nsp
irati
on
(
g c
m-2
h-1
)
VPD (kPa)
VPD insensitive
VPD sensitive
0
2
4
6
8
10
12
14
16
Xpsmp2237 Xpsmp2072 M13_Xpsmp2066 M13_Xpsmp3056 Xpsmp2206 Xpsmp2059
No o
f R
ecom
bin
an
ts
markers within LG2 DT-QTL
low Transpiration Rate in high VPD
A - from H77
B - from PRLT
H - heterozygous
Two QTL fine-mapped for low Tr at high VPD
Staygreen ILs (Stg3 – Stg B) are VPD-sensitive
0.0000
0.0020
0.0040
0.0060
0.0080
0.0100
0.0120
9 11 13 15 17
Tra
nsp
irati
on
(g
cm
-2 h
-1)
Time of the day (h)
stg1
stg3
stg4
stgB
R16
B35
Recurrent R16
Stg3
StgB
Transpiration response to VPD in Sorghum 1 - Introgression lines
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
irati
on
(g
h-1 c
m-2)
VPD (kPa)
Transpiration response to VPD in Sorghum 2 - Germplasm
Germplasm differences in VPD-sensitivity
VPD-Sensitive
VPD- Insensitive
BP= 2.58 R2 =0.68 BP= 2.51 R2 =0.76
R2 =0.89 R2 =0.83
Transpiration response to VPD in Chickpea
Transpiration response to VPD in Peanut
Mouride
If VPD < 2.09, TR = 0.0083 (VPD) – 0.002
If VPD ≥ 2.09, TR = 0.0013 (VPD) + 0.015
R² = 0.97
B UC-CB46
TR = 0.0119 (VPD) - 0.0016
R² = 0.97
D
Transpiration response to VPD in cowpea
Tolerant lines are VPD-sensitive
(water saving)
Tolerant Sensitive
Belko et al – 2012 (Plant Biology)
VPD
Tra
ns
pir
ati
on
(g
cm
-2 h
-1)
0.0 2.0 4.0
0.0
1.0
Main types of Tr response to VPD
Water Saving
Large pattern variation within/across species
VPD-sensitivity often link to drought adaptation
Large variation in all species
Often discriminate tolerant from sensitive lines
Now, systematic screening
Exciting results in other crops (rice, maize)
In summary…
The basics – Why aquaporins ?
Transpiration response to VPD
Transpiration response to AQP inhibition
AQP gene expression
AQP in the bigger picture - Drought
Apoplastic
pathway
Symplastic
Pathway
(AQP)
Sorting out the proportion of apoplastic and symplastic water transport
1 mM K4[Fe(CN)6] for 3 h Then 1 mM CuSO4.
Apoplastic pathway inhibition
Apoplastic
pathway
Symplastic
Pathway
(AQP)
Symplastic pathway inhibition
AQP inhibitors: AgNO3 – HgCl2 – H2O2
Follow-up of transpiration before/after inhibition
0.6
0.7
0.8
0.9
1
1.1
1.2N
orm
alized
Tra
nsp
irati
on
Time of the day
VPD-sensitive
VPD - insensitive
Less symplastic inhibition in VPD-sensitive
Pearl millet: Symplastic inhibition
Treatment
M322
M394
M214
M321 M592 M443 M356
M738
40 cM
0.6
0.7
0.8
0.9
1
1.1
1.2
10 30 50 70 90 110 130 150 170 190 210 230 250 270
No
rmalized
tra
nsp
irati
on
Time (minutes)
ICMR1029 1mM
ICMR2042 1mM
H77 1mM
PRLT 1mM
Symplastic inhibition in near-isogenic lines (QTL from VPD-sensitive parent)
NILs behave like QTL donor parent
M322
M394
M214
M321 M592 M443 M356
M738
40 cM
Treatment VPD-sensitive
More apoplastic inhibition in VPD-sensitive
0.00
0.20
0.40
0.60
0.80
1.00
1.20
10:10 10:40 11:10 11:40 12:10 12:40 01:10 01:40 02:10 02:40 03:10
Norm
alized
Tra
nsp
irati
on
Time
Apoplastic
inhibition
Pearl millet: Apoplastic Inhibition
VPD-sensitive
VPD - insensitive
M322
M394
M214
M321 M592 M443 M356
M738
40 cM
0
0.2
0.4
0.6
0.8
1
1.2
Norm
alized
tra
nsp
irati
on
Time
Apoplast & symplast inhibition at low VPD
Apoplastic &
Symplastic inhibition
Symplastic inhibition
Apoplastic inhibition
Apoplastic transport predominant
Low VPD small differences/effects
0
0.2
0.4
0.6
0.8
1
1.2
Norm
alized
tran
sp
irati
on
Time(mins)
Apoplast & symplast inhibition at high VPD
Symplastic inhibition
Apoplastic inhibition
Apoplastic transport less predominant
High VPD larger differences/effects
Root hydraulic conductance measurement
0.002
0.0025
0.003
0.0035
0.004
0.0045
0.005
0.0055
0.006
VPD-Sensitive VPD-Insensitive
Ro
ot
co
nd
ucti
vit
y
Root hydraulic conductivity
Symplastic transport less predominant In VPD-sensitive
Apoplast
Symplast
(AQP)
Control
Apoplast
Symplast
(AQP)
0.002
0.003
0.004
0.005
0.006
0.007
VPD-Sensitive VPD-Insensitive
Ro
ot
co
nd
ucti
vit
y
Root hydraulic conductivity
Apoplastic transport more predominant In VPD-sensitive
Control
0
0.2
0.4
0.6
0.8
1
1.2
10
30
50
70
90
110
130
150
170
190
210
230
250
270
290
310
330
350
370
390
410
NT
R
Time (mn)
Control
100 uM HgCl2
200 uM HgCl2
Before treatment
ICC 14799
0
0.2
0.4
0.6
0.8
1
1.2
10
30
50
70
90
110
130
150
170
190
210
230
250
270
290
310
330
350
370
390
410
NT
R
Time (mn)
Control
100 uM HgCl2
200 uM HgCl2
Before treatment
ICC 4958
Chickpea: Symplastic Inhibition
Less symplastic inhibition in VPD-sensitive
VPD - sensitive
VPD - insensitive
Apoplastic inhibition of chickpea genotypes
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300Time (mins)
NT
R (
No
rm
ali
sed
Tran
sp
irati
on
Rati
o)
ICC 4958 Control ICC 4958 T reatment
ICC 8058 Control ICC 8058 T reatment
ICC 867 Control ICC 867 T reatment
ICC 14799 Control ICC 14799 T reatment
1mM K4[Fe(CN)6] 0.5mM CuSO4
VPD-sensitive
VPD - insensitive
Chickpea: Apoplastic Inhibition
Less apoplastic inhibition in VPD-sensitive
Apoplast
Symplast
(AQP)
Apoplast
Symplast
(AQP)
More water via apoplast in VPD-sensitive Limited water via symplast in VPD-sensitive
Insensitive
Sensitive
VPD sensitive have apoplastic water transport
They have limited “tuning” via the symplast
More effort to be put on hydraulic measurement
Many more materials to test
In summary…
The basics – Why aquaporins ?
Transpiration response to VPD
Transpiration response to AQP inhibition
AQP gene expression
AQP in the bigger picture - Drought
VPD-insensitive
VPD-sensitive
Any difference in aquaporin expression In sorghum contrasting for VPD response??
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
irati
on
(g
pl-
1 c
m-2)
VPD (kPa)
• 14 PIPs in the Sorghum genome (4 PIP1, 10 PIP2) • Comparable to maize and rice
• RTqPCR primers designed • Putative reference genes
AQP gene expression in sorghum
• 3 conditions (low VPD am, low VPD pm / High
VPD pm) • RNA then cDNA, ref
genes
• TRqPCR From Hanna Anderberg
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
irati
on
(g
pl-
1 c
m-2)
VPD (kPa)
Morning (low VPD)
VPD-insensitive
VPD-sensitive
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
irati
on
(g
pl-
1 c
m-2)
VPD (kPa)
VPD-insensitive
VPD-sensitive
Afternoon (low VPD)
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
irati
on
(g
pl-
1 c
m-2)
VPD (kPa)
Afternoon (high VPD)
VPD-insensitive
VPD-sensitive
0
2
4
6
8
10
12
14
16
18
Low TE High TE
Hig
h V
PD
/Lo
w V
PD
PIP1;1
PIP1;2
PIP1;3
PIP1;4
PIP2;1
PIP2;2
PIP2;4
PIP2;5
PIP2;6
PIP2;7
PIP2;8
PIP2;9
PIP2;10
PIP relative expression (High VPD/Low VPD)
VPD – insensitive line increases expression of PIP2
PIP2;6
PIP2;9
PIP2;7
VPD-Insensitive VPD-Sensitive
Phylogenetic relationships of AQPs across cereals
Tentative annotation based on rice
Tentative annotation based on sorghum
Tentative annotation based on maize
PIP1;1 Pip1;3/4 pip1.1 PIP1;2 Pip1;3/4 Pip1;3/4 PIP1;3 pip1.5 pip1.5 PIP1;4 pip1.6 pip1.6
PIP2;10 pip2.7 pip2.7 PIP2;10 pip2.2 pip2.1
PIP2;2 hypothetical protein PIP2;2
PIP2;3 pip PIP2;4 pip2.3 pip2.4 PIP2;5 pip2.5 pip2.5 PIP2;6 pip2.6 pip2.5 PIP2;7 pip 95%PIP2;1 PIP2;8 pip2.6 pip2.6 PIP2;9 pip2.6 pip2.3
Tentative annotation in rice, sorghum, maize
VPD
insensitive
High VPD Low VPD
VPD
sensitive VPD
insensitive
VPD
sensitive
0.00.10.20.30.40.50.60.7
VPD-sensitive_LVPD VPD-insensitive_LVPD VPD-sensitive_HVPD VPD_insensitive_Hvpd
ban
d i
nte
nsi
ty
More AQP protein in VPD–insensitive line
AQP protein measurement with maize PIP2;6 antibodies
Total RNA Ist S trand cDNA
Degenerate primer
designing using
other closely related
species as a source
M -Ve 1 2 3 4 5 6 7 8 9
PCR amplifications of Aqp genes from cDNA.
Cloning of PgAqp genes into pCR8/GW/TOPO vector Plasmid DNA isolated for positive Aqp clones
Sequencing
and analysis
Cloning of Aquaporin genes in pearl millet (homology based cloning strategy) .
Phylogentic relationships between pearl millet, maize
and rice Aquaporin proteins
0.25
0.5
1
2
4
8
16
L R L R L R L R
1122 1086 1152 1078
PIP1.1 PIP1.2 PIP2.1 PIP2.3 PIP2.6 TIP1.1 TIP2.2R
ela
tive e
xp
ressio
n
Genotype and Stress conditions
VPD - Insensitive VPD - Sensitive
PIP relative expression (Low VPD)
High AQP expression in VPD-insensitive line
0.25
0.5
1
2
4
8
16
L R L R L R L R
1122 1086 1152 1078
PIP1.1 PIP1.2 PIP2.1 PIP2.3 PIP2.6 TIP1.1 TIP2.2
Genotype and Stress conditions
PIP relative expression (High VPD/Low VPD) R
ela
tive e
xp
ressio
n
VPD - Insensitive VPD - Sensitive
Even Higher AQP expression in VPD-insensitive line under high VPD
Increase in AQP expression in VPD-insensitive under high VPD
Transcript abundance & protein agree
Up regulation in both leaves and roots
On-going work in other species
Comparative genomics
In Summary…
The basics – Why aquaporins ?
Transpiration response to VPD
Transpiration response to AQP inhibition
AQP gene expression
AQP in the bigger picture - Drought
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tran
spir
ati
on
(g
pl-1
cm
-2)
VPD (kPa)
Why are VPD-sensitive sorghum so interesting?
VPD-insensitive
VPD-sensitive
VPD-sensitive have high transpiration efficiency
2.0
3.0
4.0
5.0
6.0
7.0
152 Germplasm tested
TE
10 lowest TE are VPD-Insensitive
10 highest TE are VPD-sensitive
High TE lines limit transpiration at high VPD
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
TE
0
0.005
0.01
0.015
0.02
0.025
0.03
1 2 3 4 5 6 7 8
Tra
nsp
irati
on
(g
cm
-2 h
-1)
VPD (kPa)
Same result in sorghum and pearl millet
What about pearl millet?
Low TE (VPD-Insensitive)
High TE (VPD-Sensitive)
grain yield gain (low TR)
-300
-200
-100
0
100
200
300
400
0 500 1000 1500 2000 2500 3000 3500
original yield (kg/ha)
yie
ld g
ain
(kg
/ha)
1 postflowering
2 flowering
3 postflowering-relieved
4 no stress
5 prefloweringOriginal yield (kg ha-1)
0
Yield increase (kg/ha) with transpiration sensitivity to high VPD: Rabi sorghum
Yie
ld i
ncrease
-1 0 +33
Crop modelling used to predict trait effects
15-30% yield increase at high latitudes
% yield increase with transpiration sensitivity to high VPD: Peanut
Lysimetric evaluation
Transpiration in pots
0.000
0.004
0.008
0.012
0.016
0.020
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
ira
tio
n
(g
cm
-2 h
-1)
VPD
Low TE
High TE
0
1
2
3
4
5
6
7
Low TE High TE
TE
grain yield gain (low TR)
-300
-200
-100
0
100
200
300
400
0 500 1000 1500 2000 2500 3000 3500
original yield (kg/ha)
yie
ld g
ain
(kg
/ha)
1 postflowering
2 flowering
3 postflowering-relieved
4 no stress
5 preflowering
Original yield (kg ha-1)
0
AQP gene expression
Modeling of Tr restriction effect on yield
The VPD response lead to higher TE
It is itself related to differences in AQP gene expression
Major yield increase possible across crops
Breeding (donors identified)
Harness genetics – Phenotyping (new platform)
In Summary…
Thank you
Collaborators: F. Chaumont (Univ. Louvain) H. Anderberg (Lund Univ.)
Donors: ICRISAT ACIAR DFID B&MGF
Technicians / Data analyst: Srikanth Malayee Rekha Badham
Students: M Tharanya S Sakthi T Rajini S Medina K Aparna
Colleagues: J Kholova / P Suddhakar Reddy / G Barzana / JM Devi/ KK Sharma / T Shah / P Bhatnagar / Hima Bindhu / RK Varshney / R Srivastava / SP Deshpande
Special thanks to: ICRISAT MG/RC Gov. Board
Lysimetric evaluation
Transpiration in pots
0.000
0.004
0.008
0.012
0.016
0.020
0.62 1.05 1.58 2.01 2.43 3.05 3.45
Tra
nsp
ira
tio
n
(g
cm
-2 h
-1)
VPD
Low TE
High TE
0
1
2
3
4
5
6
7
Low TE High TE
TE
grain yield gain (low TR)
-300
-200
-100
0
100
200
300
400
0 500 1000 1500 2000 2500 3000 3500
original yield (kg/ha)
yie
ld g
ain
(kg
/ha)
1 postflowering
2 flowering
3 postflowering-relieved
4 no stress
5 preflowering
Original yield (kg ha-1)
0
AQP gene expression
Modeling of Tr restriction effect on yield
Xpsmp2237
Xpsmp2072
17.1 cM
Xpsmp2066
12.0 cM
Xpsmp3056
19.1 cM
Xpsmp2206
14.2 cM
Xpsmp2059
2.5 cM
Grain Yld Flowering time
Grain Yld
Allele effect
Xibmsp44
Xibmsp4
Xibmsp7
Xibmsp60 Xibmsp34
Xibmsp14 Xibmsp24
Xibmsp31 Xibmsp11
Xibmsp62 Xibmsp27 Xibmsp9 Xibmsp12
Xibmsp15
Xibmsp23
PRLT 2/89-33 H 77/833-2
Increased decreased
decreased Increased
Flowering time
Increased decreased
decreased Increased
Stay green decreased Increased
Increased decreased
Tr rate Increased decreased
Tr rate decreased Increased
Stay green
Candidate genes
Zn finger CCCH-type, serine/threonine protein kinase, MADS-box, acetyl CoA carboxylase
Stay green