Organ-specific phosphorus-allocation patterns and transcript profiles linked to P efficiency in wheat Tariq Aziz 1,2 & Ricarda Jost 2 1 University of Agriculture, Faisalabad, Pakistan 2 School 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: ‘smarter’ plants with improved P-use efficiency from: MacDonald et al. (2012) Environ. Res. Lett. 7 Crop P use efficiency [%] Total P supply to each crop exported [%]

Phosphorus efficient wheat A/Prof Tariq Aziz

15 cm MacheteChinese day growth on 0.2 mM KH 2 PO 4 MacheteChinese 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 (-P i ), DW (-P i ) vs. DW (+P i ), [P] int. vs. P i supplied, shoot DW per unit P in plant Machete = inefficient genotype (3 criteria) Chinese = efficient genotype (2-3criteria, 3/99 genotypes)

Harvesting scheme 25 day-old P-sufficient seedlings, transferred to nutrient solution with either no P i or with 200 µM P i 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

Aziz et al. (2014) PCE 37 = Machete = Chinese Chinese maintains higher root biomass * p ≤ 0.05 rel. to Machete RGR = rel. growth rate time after transfer [d]

Chinese has a ‘smart’ P allocation pattern +P (C/M)-P (C/M) PiPi PoPo PiPi PoPo PiPi PoPo PiPi PoPo PiPi PoPo PiPi PoPo PiPi PoPo PiPi PoPo fine roots stem mature root mature leaf young leaf tip middle base middle tip PiPi PoPo PiPi PoPo Aziz et al. (2014) PCE P (C/M)-P (C/M) 18 days after transfer

TaPHT1;2 is differentially expressed in sink tissues +P (C/M)-P (C/M) ABAB ABAB ABAB ABAB fine roots stem mature root mature leaf young leaf tip middle base middle tip ABAB Aziz et al. (2014) PCE  C t (log2) A = TaPHT1;2 B = TaIPS1 +P (C/M)-P (C/M) 18 days after transfer

= P-sufficient Machete = P-limited Chinese = P-limited Machete = P-sufficient Chinese TaPHT1;2 is not suppressed by high P i supply in P-efficient Chinese * p ≤ 0.05 rel. to treated Machete rel. expression level [40 –  C t ] - 18 days after transfer

Summary of responses in P-limited Chinese fine roots stem mature root tip middle base middle tip Aziz et al. (2014) PCE SSRR mature leafyoung leaf = rel. starch levelsS = rel. ribosome #R = rel. P i uptake capacity

Summary of responses in P-sufficient Chinese fine roots stem mature root tip middle base Aziz et al. (2014) PCE middle S mature leafyoung leafS S = rel. starch levelsS = rel. ribosome #R = rel. P i uptake capacity baseRS tip

Conclusions A phosphorus-efficient wheat cultivar  Remobilises P to supply source leaves when P-limited  Can quickly convert available P i 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 !

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!