Organ-specific phosphorus-allocation patterns and transcript profiles linked to P efficiency in wheat

Tariq Aziz1,2 & Ricarda Jost2

1University of Agriculture, Faisalabad, Pakistan2School of Plant Biology, The University of Western Australia

from: Cordell et al. (2009) Preferred future phosphorus scenarios: A framework for meeting long-term phosphorus needs for global food demand. IWA Publishing.

‘smarter’ plants with improved P-use efficiency

from: http://phosphorusfutures.net.

‘smarter’ plants with improved P-use efficiency

from: MacDonald et al. (2012) Environ. Res. Lett. 7

Cro

p P

use

eff

icie

ncy

[%

]250

200

150

100

50

0100 20 30 40 50

Total P supply to each crop exported [%]

Phosphorus efficient wheat

A/Prof Tariq Aziz

15 cm

15 cm

Machete Chinese 80-55

7-day growth on 0.2 mM KH2PO4

Machete Chinese 80-55

7-day growth without phosphate

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)

Harvesting scheme

25 day-old P-sufficient seedlings, transferred to nutrient solution with either no Pi orwith 200 µM Pi and harvest after 3, 7 and 18 days of treatment

Organs harvested: mature vs. fine rootsyoung vs. mature leavesleaf sections = tip / middle / basal

Aziz et al. (2014) PCE 37

= Machete

= Chinese 80-55

Chinese 80-55 maintains higher root biomass

* p ≤ 0.05 rel. to Machete

RGR = rel. growth rate

time after transfer [d] time after transfer [d]

0 3 7 18 3 7 18 0 3 7 18 3 7 18

Chinese 80-55 has a ‘smart’ P allocation pattern

+P (C/M) -P (C/M)

Pi Po Pi Po

Pi Po Pi Po

Pi Po Pi Po

Pi Po Pi Pofine roots

stem

mature root

mature leaf

young leaf

tip

middle

base

base

middle

tip

Pi Po Pi Po

Aziz et al. (2014) PCE 37

+5

+2.5

0

-2.5

-5

+P (C/M) -P (C/M)

18 days after transfer

TaPHT1;2 is differentially expressed in sink tissues

+P (C/M) -P (C/M)

A B A B

A B A B

A B A B

A B A Bfine roots

stem

mature root

mature leaf

young leaf

tip

middle

base

base

middle

tip

A B A B

Aziz et al. (2014) PCE 37

+5

+2.5

0

-2.5

-5

-Ct (log2)

A = TaPHT1;2 B = TaIPS1

+P (C/M) -P (C/M)

18 days after transfer

= P-sufficient Machete

= P-limited Chinese 80-55

= P-limited Machete

= P-sufficient Chinese 80-55

TaPHT1;2 is not suppressed by high Pi supplyin P-efficient Chinese 80-55

* p ≤ 0.05 rel. to treated Machete

rel.

expr

essi

on le

vel [

40 –

C

t]

PT2;1 PT3;1 IPS1PT1;5 PT1;8PT1;2

Young Leaf Base

24

26

28

30

32

34

36

38

40

42

44

46

48

*

- 18 days after transfer

Summary of responses in P-limited Chinese 80-55

fine roots

stem

mature root

tip

middle

base

base

middle

tip

Aziz et al. (2014) PCE 37

+5

+2.5

0

-2.5

-5

S

S R

R

mature leafyoung leaf

= rel. starch levelsS = rel. ribosome #R

= rel. Pi uptake capacity

Summary of responses in P-sufficient Chinese 80-55

fine roots

stem

mature root

tip

middle

base

Aziz et al. (2014) PCE 37

+5

+2.5

0

-2.5

-5

middle

S

mature leafyoung leaf

S

S

= rel. starch levelsS = rel. ribosome #R

= rel. Pi uptake capacity

baseR S

tip

Conclusions

A phosphorus-efficient wheat cultivar

Þ Remobilises P to supply source leaves when P-limited

Þ Can quickly convert available Pi into organic compounds for growth

Þ Restricts ribosome numbers in P-limited sink tissues to off-setdevelopment (?)

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 !

Collaborators:

Zed Rengel, School of Earth & Environment, UWA

Acknowledgements

Australian Research Council

School of Plant Biology, UWA:

Oliver Berkowitz*

Patrick M. Finnegan

Hans Lambers

Postdoctoral Fellowship Program (PDFP) of the Higher Education Commission of Pakistan (T. Aziz)

* ARC Centre of Excellence for Plant Energy Biology, UWA

Thank you!