Transcript Organ-specific phosphorus-allocation patterns and transcript profiles

Organ-specific phosphorus-allocation patterns and
transcript profiles linked to P efficiency in wheat
Tariq Aziz1,2 & Ricarda Jost2
1University
of Agriculture, Faisalabad, Pakistan
2School of Plant Biology, The University of Western Australia
‘smarter’ plants with improved P-use efficiency
from: Cordell et al. (2009) Preferred future phosphorus scenarios: A framework for
meeting long-term phosphorus needs for global food demand. IWA Publishing.
Crop P use efficiency [%]
‘smarter’ plants with improved P-use efficiency
250
200
150
100
50
0
0
10
20
30
40
50
Total P supply to each crop exported [%]
from: MacDonald et al. (2012) Environ. Res. Lett. 7
from: http://phosphorusfutures.net.
Phosphorus efficient wheat
A/Prof Tariq Aziz
Osborne and Rengel 2002 Aust. J. Agric. Res. 52 & 53:
• screen of 99 wheat genotypes on iron phosphate / phytate as sole P source
(deficient vs. sufficient supply)
• 4 criteria – shoot DW (-Pi), DW (-Pi) vs. DW (+Pi), [P]int. vs. Pi supplied,
shoot DW per unit P in plant
• Machete = inefficient genotype (3 criteria)
• Chinese 80-55 = efficient genotype (2-3criteria, 3/99 genotypes)
7-day growth on 0.2 mM KH2PO4
7-day growth without phosphate
Chinese 80-55
15 cm
15 cm
Machete
Machete
Chinese 80-55
Harvesting scheme
25 day-old P-sufficient seedlings, transferred to nutrient solution with either no Pi or
with 200 µM Pi and harvest after 3, 7 and 18 days of treatment
Organs harvested:
mature vs. fine roots
young vs. mature leaves
leaf sections = tip / middle / basal
Chinese 80-55 maintains higher root biomass
= Machete
= Chinese 80-55
RGR = rel. growth rate
0
3
7
18
3
7
time after transfer [d]
18
0
3
7
18
3
7
18
* p ≤ 0.05 rel. to Machete
time after transfer [d]
Aziz et al. (2014) PCE 37
Chinese 80-55 has a ‘smart’ P allocation pattern
18 days after transfer
+P (C/M) -P (C/M)
young leaf
Pi Po
+5
+2.5
0
Pi Po
-2.5
tip
-5
middle
+P (C/M)
base
Pi Po
-P (C/M)
Pi Po mature leaf
tip
Pi Po
Pi Po
middle
stem
base
Pi Po
fine roots
Pi Po
Pi Po
Pi Po
mature root
Aziz et al. (2014) PCE 37
TaPHT1;2 is differentially expressed in sink tissues
A = TaPHT1;2
18 days after transfer
+P (C/M) -P (C/M)
young leaf
A B
A
B = TaIPS1
+5
+2.5
0
B
-2.5
tip
-5
middle
+P (C/M)
base
A
B
-P (C/M)
-Ct (log2)
A B
mature leaf
tip
A B
A
B
middle
stem
base
A B
fine roots
A
B
A B
A B
mature root
Aziz et al. (2014) PCE 37
rel. expression level [40 – Ct]
TaPHT1;2 is not suppressed by high Pi supply
in P-efficient Chinese 80-55
48
46
Young Leaf Base - 18 days after transfer
44
42
= P-sufficient Machete
40
38
**
36
34
*
*
32
26
24
= P-sufficient Chinese 80-55
= P-limited Chinese 80-55
30
28
= P-limited Machete
*
PT1;2 PT1;5 PT1;8 PT2;1 PT3;1 IPS1
* p ≤ 0.05 rel. to treated Machete
Summary of responses in P-limited Chinese 80-55
S
young leaf
= rel. starch levels
R
= rel. ribosome #
mature leaf
+5
+2.5
tip
0
-2.5
-5
middle
tip
base
S R
middle
base
stem
fine roots
S
R
= rel. Pi uptake capacity
mature root
Aziz et al. (2014) PCE 37
Summary of responses in P-sufficient Chinese 80-55
S
= rel. starch levels
R
= rel. ribosome #
young leaf
mature leaf
+5
+2.5
tip
0
-2.5
middle
base
stem
S
-5
tip
S
middle
S
fine roots
= rel. Pi uptake capacity
R S
base
mature root
Aziz et al. (2014) PCE 37
Conclusions
A phosphorus-efficient wheat cultivar
 Remobilises P to supply source leaves when P-limited
 Can quickly convert available Pi into organic compounds for growth
 Restricts ribosome numbers in P-limited sink tissues to off-set
development (?)
Why bring post‐genomics into the P‐impoverished bush?
Yves Gibon (2014) Commentary in Plant, Cell & Environment 37(6)
Sulpice et al. (2014) Plant, Cell & Environment 37(6)
 Please visit posters in session 3 – P utilisation and signalling in plants !
Acknowledgements
School of Plant Biology, UWA:
Oliver Berkowitz*
Patrick M. Finnegan
Collaborators:
Zed Rengel,
School of Earth & Environment, UWA
Hans Lambers
* ARC Centre of Excellence for Plant Energy Biology, UWA
Australian Research Council
Postdoctoral Fellowship Program (PDFP) of the
Higher Education Commission of Pakistan (T. Aziz)
Thank you!