Associate Professor Oula Ghannoum

Oula GhannoumA/Professor Oula Ghannoum graduated with a BSc (Honours) in Plant Biochemistry (UNSW, 1993) and obtained her PhD in Plant Physiology (UWS, 1998). She has >15 years of research experience in plant physiology and biochemistry. In 2001, Oula was awarded the prestigious ARC Postdoctoral Fellowship to work at RSBS, ANU, and in 2007, she was awarded an Independent Postdoctoral Fellowship to work at the Centre for Plant and Food Science (a precursor to HIE). 

In 2010, Oula was appointed Senior Researcher at the Hawkesbury Institute for the Environment (HIE). Her current position includes the following academic and leadership roles

  • Unit coordinator/Lecturer (Plant Physiology, 300865, 2nd year undergraduate unit)
  • Supervisor and co-supervisor of PhD and Honours students
  • Deputy theme leader 'Animals, Plants and Interactions', HIE
  • Member of Teaching committee, HIE
  • Associate Editor, Functional Plant Biology, CSIRO Publishing
  • UWS Node/Deputy Programme leader, ARC Centre of Excellence for Translational Photosynthesis ( (opens in a new window)
Dr Ghannoum within the Lab
Dr Ghannoum outside a WTC

Oula contributes to advancing photosynthesis research in two main areas: the environmental and molecular regulation of C4 photosynthesis and the response of C3 and C4 plants to climate change.

Currently, her research focusses on the links between Rubisco catalysis, the CO2 concentrating mechanism and resource use efficiency in C4 plants. This research is conducted in collaboration with colleagues at ANU and CSIRO-PI and has significant translational potential for crop improvement and management of Australia's fragile rangelands.

A/Professor Ghannoum collaborates with Australian and Chinese breeders in large-scale crop improvement projects for dry environments (sugarcane, sorghum) and eCO2 futures (wheat).

Together with researchers at Western Sydney University, Oula is working on elucidating leaf-level processes which underlie the growth and water use responses of eucalypts to environmental change, in addition to their implications on understorey dynamics and fire regimes in water- and nutrient-limited Australian woodlands.


Areas of Research / Teaching Expertise

C4 photosynthesis
Global change biology
Unit Coordinator for Plant Physiology (300865)

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Awards and Recognition

2001-2003: Australian Postdoctoral Fellowship, ARC, $185,766
1998: Christine Wieneke New Researcher Award, UWS, $3,000
1998:  Visiting Fellowship, Japanese Science and Technology, $8,000

Grants / Current Projects

External Funding:

  • 2014 – 2020: ARC Centre of Excellence, $2M from ARC and 0.7M from UWS (total CE funding $22M) - CE140100015
    ARC Centre of Excellence for Translational Photosynthesis.
    Investigators: M Badger; S von Caemmerer; John Evans; G Farquhar; G Price; S Whitney; G Hammer; D Jordan; M Chen; O Ghannoum; R Furbank; W Quick
  • 2014 – 2016: ARC Discovery, $315,000 - DP140103415
    Is physiological flexibility of forest trees constrained by home climate in a rapidly warming world?
    Investigators: MG Tjoelker, O Ghannoum, J Drake, DT Tissue, PB Reich
  • Crop traits for productivity in a high carbon dioxide world under drought and heat [via University of Melbourne]
    2013-2016: DAFF via ACRG
    Investigators: M Tausz, S Tausz-Posch, O Ghannoum, R Duursma, G Fitzgerald, R Armstrong, G O'Leary, J Nuttall, 
  • Rubisco for all climates: unlocking the enzyme's structure-function relations for more efficient photosynthesis.
    2012 – 2014: ARC Discovery, $310,000
    Investigators: SM Whitney, O Ghannoum
  • Impacts of climate change on nitrogen uptake by eucalypt seedlings.
    2010: Australian Institute of Nuclear Science & Engineering-AINSE Research Award, $6,108
    Investigators: O. Ghannoum, P. Milham
  • Causes and consequences of the differences in leaf biochemistry and structure between NAD-ME and NADP-ME C4 grasses (completed).
    2001 – 2003: ARC Postdoctoral Fellowship, $185,766
    APD Fellow: O Ghannoum

Internal Funding:

  • A Phytotron for Multitrophic Interactions on Plant Production Systems.
    2009: UWS Research Infrastructure Fund, $300,000
    Investigators: M. Riegler, O. Ghannoum, and B. Bellotti
  • Using metabolomics to study the response of Australia's tropical grasses to phosphorus deficiency (completed).
    2005: UWS International Research Initiative Scheme, $17,382
    Investigators: O Ghannoum, JP Conroy and MJ Paul
  • Using transcriptomics to compare the effects of phosphorus deficiency on the model plants arabidopsis and maize (completed).
    2005: UWS Internal Research Grant Scheme, $23,500
    Investigators: V Higgins and O Ghannoum
  • Proteomics of the bundle sheath and mesophyll thylakoid membrane in maize (completed).
    2004: UWS Research Seed Grant Scheme, $7,500
    Investigator: O Ghannoum
  • Relating carbon and nitrogen metabolism regulation to osmolyte accumulation in C4 grasses under water stress (completed).
    1998: UWS Internal Research Grant Scheme, $12,000
    Investigator: O Ghannoum
  • Response of C3 and C4 Panicum grasses to CO2 enrichment (completed).
    1995 – 1996: ANU Collaborative Research Scholarship, $14,000
    PhD candidate: O Ghannoum

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Student supervision and research projects

Research opportunities:

Following the depletion of CO2 concentration ([CO2]) in the atmosphere 30 million years ago, the efficiency of C3 photosynthesis was reduced in arid and hot environments, due to increased photorespiration which leads to loss of energy and carbon fixed. 

C4 photosynthesis has evolved to overcome the limitations of ancestral C3 photosynthetic pathway by operating a CO2 concentration mechanism which raises CO2 at the site of Rubisco and suppresses photorespiration in air. C4 plants are more productive and resource use efficient than the more prevalent C3 plants. At present, C4 plants constitute 3% of the world's species and C4-dominated grasslands contribute up to 20% of global primary productivity. About 50% of C4 species are grasses with 15 distinct evolutionary origins distributed over 370 genera and 4600 species. Further, C4 plants are divided into three biochemical subtypes following the major C4 acid decarboxylase in the bundle sheath cells: NAD malic enzyme (NAD-ME), NADP-ME and PEP carboxykinase (PCK).

PhD and Honours research projects are available for eligible and motivated students to work with Dr Ghannoum on the diversity and regulation of CO2 concentrating mechanisms in C4 plants. Projects investigating the environmental and molecular regulation of the C3, C4 and C3-C4 photosynthetic pathways are also available. The projects are addressed using a combination of gas exchange-stable isotope, biochemical and/or molecular tools. Interested students are encouraged to contact Dr Ghannoum directly to discuss their suitability and the project details.


Research students:

  • Sachin Chavan (PhD candidate, 2014-ongoing): Crop traits for productivity in a high CO2 world under drought and heat Supervisory panel: Ghannoum and Duursma.
  • Varsha Pathare (PhD candidate, 2014-ongoing): Communities of the future: How will eCO2 and altered water availability affect woodland understorey plant species? Supervisory panel: Ellsworth and Ghannoum.
  • Balasaheb Sonawane (PhD candidate, 2013-ongoing): Environmental and molecular factors controlling the efficiency of the CO2 concentrating mechanism in C4 grasses. Supervisory panel: Ghannoum, Sharwood and Whitney.
  • Harshini Pinto (PhD candidate, 2011-2014): Resource use efficiency of C4 grasses with different evolutionary origins. Supervisory panel: Ghannoum, Tissue, Sharwood and Conroy.
  • Josephine Ontedhu (PhD candidate, 2010-2014): Interaction of phosphorus nutrition with eucalypt responses to elevated [CO2] and temperature. Supervisory panel: Tissue, Ghannoum and Milhamonours Supervision

Honours Students

  • Simon Reeves (Honours candidate, completed 2013): Contrasting the effect of climate warming on the photosynthesis of Eucalyptus provenances. Supervisory panel: Sharwood and Ghannoum.
  • Anthony Newton (Honours candidate, completed 2012): Investigating the molecular plasticity of C4 photosynthesis. Supervisory panel: Sharwood and Ghannoum.
  • Gyro Sherwin (Honours candidate, completed 2011): Impact of industrial-age climate change on nitrogen uptake and partitioning in Eucalyptus. Supervisory panel: Ghannoum, George, Kannangara, Tissue
  • Harshini Pinto (Honours candidate, completed 2010): Resource use efficiency of C4 grasses with different evolutionary origins. Supervisory panel: Tissue and Ghannoum

Selected Publications

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Book Chapters

Ghannoum O, von Caemmerer S, Taylor N, Millar AH (2013). CO2 assimilation and respiration in "Plants in Action". 2nd edition: (opens in a new window). (Eds. R Munns, S Schmidt, C Beveridge). Australian Society of Plant Scientists.

Ghannoum O, Evans JR, von Caemmerer S, (2011) Nitrogen and water use efficiency of C4 plants, in C4 Photosynthesis and Related CO2 Concentrating Mechanisms, Advances in Photosynthesis and Respiration series, pp 129 - 146 (Eds) Raghavendra AS, Sage RF, Springer, Berlin

Ghannoum O, Searson M, Conroy J, (2006) Nutrient and water demands of plants under climate change, in Agroecosystems in a Changing Climate, Advances in Agroecology Series 12, (Eds) Newton PCD, Edwards G, Carran A, & Niklaus P, CRC Press, Boca Raton, FL, USA, pp 53–83

Journal Articles

Aspinwall MJ, Drake JE, Campany C, Vårhammar A, Ghannoum O, Tissue DT, Reich PB, Tjoelker MG, (2016) 'Convergent acclimation of leaf photosynthesis and respiration to prevailing ambient temperatures under current and warmer climates in Eucalyptus tereticornis', New Phytologist, vol.212, no.2, pp 354-367

Ghannoum O, (2016) 'How can we breed for more water use-efficient sugarcane?', Journal of Experimental Botany, vol.67, no.3, pp 557-559

Pinto H, Powell JR, Sharwood RE, Tissue DT, Ghannoum O, (2016) 'Variations in nitrogen use efficiency reflect the biochemical subtype while variations in water use efficiency reflect the evolutionary lineage of C4 grasses at inter-glacial CO2', Plant, Cell and Environment, vol.39, no.3, pp 514-526

Sharwood RE, Ghannoum O, Whitney SM, (2016) 'Prospects for improving CO2 fixation in C3-crops through understanding C4-Rubisco biogenesis and catalytic diversity', Current Opinion in Plant Biology, vol.31, pp 135-142

Sharwood RE, Sonawane BV, Ghannoum O, Whitney SM, (2016) 'Improved analysis of C4 and C3 photosynthesis via refined in vitro assays of their carbon fixation biochemistry', Journal of Experimental Botany, vol.67, no.10, pp 3137-3148 

Drake JE, Aspinwall MJ, Pfautsch S, Rymer PD, Reich PB, Smith RA, Crous KY, Tissue DT, Ghannoum O, Tjoelker MG, (2015) 'The capacity to cope with climate warming declines from temperate to tropical latitudes in two widely distributed Eucalyptus species', Global Change Biology, vol.21, no.1, pp 459-472

Lin Y-S, Medlyn BE, Duursma RA, Prentice IC, Wang H, Baig S, Eamus D, De Dios VR, Mitchell P, Ellsworth DS, De Beeck MO, Wallin G, Uddling J, Tarvainen L, Linderson M-L, Cernusak LA, Nippert JB, Ocheltree TW, Tissue DT, Martin-StPaul NK, Rogers A, Warren JM, De Angelis P, Hikosaka K, Han Q, Onoda Y, Gimeno TE, Barton CVM, Bennie J, Bonal D, Bosc A, Löw M, Macinins-Ng C, Rey A, Rowland L, Setterfield SA, Tausz-Posch S, Zaragoza-Castells J, Broadmeadow MSJ, Drake JE, Freeman M, Ghannoum O, Hutley LB, Kelly JW, Kikuzawa K, Kolari P, Koyama K, Limousin J-M, Meir P, Da Costa ACL, Mikkelsen TN, Salinas N, Sun W, Wingate L, (2015) 'Optimal stomatal behaviour around the world', Nature Climate Change, vol.5, no.5, pp 459-464 

Chehine C, Holford P, Ghannoum O, Collins D, Conroy JP, Milham PJ, (2014) 'Transpiration influences cadmium uptake by baby leaf Spinach (Spinacia Oleracea L.)', American Journal of Agricultural and Biological Science, vol.9, no.4, pp 523-533

Pinto H, Sharwood RE, Tissue DT, Ghannoum O (2014). Photosynthesis of C3, C3-C4 and C4 grasses at glacial CO2. Journal of Experimental Botany, vol.65 , no.13 , pp 3669-3681 , Special Issue SI.

Sharwood RE, Sonawane BV, Ghannoum O, (2014) 'Photosynthetic flexibility in maize exposed to salinity and shade', Journal of Experimental Botany, vol.65, no.13, pp 3715-3724 Special Issue: SI  

von Caemmerer S, Ghannoum O, Pengelly JL, Cousins AB (2014). Carbon isotope discrimination as a tool to explore C4 photosynthesis. Journal of Experimental Botany, vol.65, no.13 , pp 3459-3470 , Special Issue SI.

Anderson IC, Drigo B, Keniry K, Ghannoum O, Chambers SM, Tissue DT, Cairney JW, (2013) 'Interactive effects of preindustrial, current and future atmospheric CO2 concentrations and temperature on soil fungi associated with two Eucalyptus species', FEMS Microbiology Ecology, vol.83, no.2, pp 425-437

De Dios VR, Turnbull MH, Barbour MM, Ontedhu J, Ghannoum O, Tissue DT, (2013) 'Soil phosphorous and endogenous rhythms exert a larger impact than CO 2 or temperature on nocturnal stomatal conductance in Eucalyptus tereticornis', Tree Physiology, vol.33, no.11, pp 1206-1215

Franks PJ, Adams MA, Amthor JS, Barbour MM, Berry JA, Ellsworth DS, Farquhar GD, Ghannoum O, Lloyd J, McDowell N, Norby RJ, Tissue DT, von Caemmerer S, (2013) 'Sensitivity of plants to changing atmospheric CO2 concentration: From the geological past to the next century', New Phytologist, vol.197, no.4, pp 1077-1094

Lewis JD, Smith RA, Ghannoum O, Logan BA, Phillips NG, Tissue DT, (2013) 'Industrial-age changes in atmospheric [CO2] and temperature differentially alter responses of faster- and slower-growing Eucalyptus seedlings to short-term drought', Tree Physiology, vol.33, no.5, pp 475-488

Sherwin GL, George L, Kannangara K, Tissue DT, Ghannoum O, (2013) 'Impact of industrial-age climate change on the relationship between water uptake and tissue nitrogen in eucalypt seedlings', Functional Plant Biology, vol.40, no.2, pp 201-212

Smith RA, Lewis JD, Ghannoum O, Tissue DT, (2012) 'Leaf structural responses to pre-industrial, current and elevated atmospheric [CO2] and temperature affect leaf function in Eucalyptus sideroxylon', Functional Plant Biology, vol.39, no.4, pp 285-296  

Xu C-Y, Salih A, Ghannoum O, Tissue DT, (2012) 'Leaf structural characteristics are less important than leaf chemical properties in determining the response of leaf mass per area and photosynthesis of Eucalyptus saligna to industrial-age changes in [CO2] and temperature', Journal of Experimental Botany, vol.63, no.16, pp 5829-5841

Ghannoum O, Way DA, (2011) 'On the role of ecological adaptation and geographic distribution in the response of trees to climate change', Tree Physiology, vol.31, no.12, pp 1273-1276

Phillips NG, Attard RD, Ghannoum O, Lewis JD, Logan BA, Tissue DT, (2011) 'Impact of variable [CO2] and temperature on water transport structure-function relationships in Eucalyptus', Tree Physiology, vol.31, pp 945-952

Pinto H, Tissue DT, Ghannoum O, (2011) 'Panicum milioides (C3-C4) does not have improved water or nitrogen economies relative to C3 and C4 congeners exposed to industrial-age climate change', Journal of Experimental Botany, vol.62, pp 3223-3234

Logan BA, Hricko C, Lewis JD, Ghannoum O, Phillips NG, Smith RA, Conroy JP, Tissue DT, (2010) 'Examination of pre-industrial and future [CO2] reveals the temperature-dependent CO2 sensitivity of light energy partitioning at PSII in eucalypts', Functional Plant Biology, vol.37, pp 1041-1049

Ghannoum O, Phillips NG, Sears MA, Logan BA, Lewis JD, Conroy JP, Tissue DT, (2010) 'Photosynthetic responses of two eucalypts to industrial-age changes in atmospheric [CO2] and temperature', Plant, Cell and Environment, vol.33, pp 1671-1681

Edwards EJ, Osborne CP, Strömberg CAE, Smith SA, Bond WJ, Christin P-A, Cousins AB, Duvall MR, Fox DL, Freckleton RP, Ghannoum O, Hartwell J, Huang Y, Janis CM, Keeley JE, Kellogg EA, Knapp AK, Leakey ADB, Nelson DM, Saarela JM, Sage RF, Sala OA, Salamin N, Still CJ, Tipple B, (2010) 'The origins of C4 grasslands: Integrating evolutionary and ecosystem science', Science, vol.328, pp 587-591

Cousins AB, Ghannoum O, von Caemmerer S, Badger MR, (2010) 'Simultaneous determination of Rubisco carboxylase and oxygenase kinetic parameters in Triticum aestivum and Zea mays using membrane inlet mass spectrometry', Plant, Cell and Environment, vol.33, pp 444-452

Ghannoum O, Phillips NG, Conroy JP, Smith RA, Attard RD, Woodfield R, Logan BA, Lewis JD, Tissue DT, (2010) 'Exposure to pre-industrial, current and future atmospheric [CO2] and temperature differentially affects growth and photosynthesis in Eucalyptus', Global Change Biology, vol.16, pp 303-319

Ghannoum O, (2009) 'C4 photosynthesis and water stress', Annals of Botany, vol.103, pp 635-644 (Invited Review)

Ghannoum O, Paul MJ, Ward JL, Beale MH, Corol D-I, Conroy JP, (2008) 'The sensitivity of photosynthesis to phosphorus deficiency differs between C3 and C4 tropical grasses', Functional Plant Biology, vol.35, pp 213-221

Ghannoum O, Conroy JP, (2007) 'Phosphorus deficiency inhibits growth in parallel with photosynthesis in a C3 (Panicum laxum) but not two C4 (P. coloratum and Cenchrus ciliaris) grasses', Functional Plant Biology, vol.34, pp 72-81

Dwyer SA, Ghannoum O, Nicotra A, von Caemmerer S, (2007) 'High temperature acclimation of C4 photosynthesis is linked to changes in photosynthetic biochemistry', Plant, Cell and Environment, vol.30, pp 53-66

Ghannoum O, Evans JR, Chow WS, Andrews TJ, Conroy JP, and von Caemmerer S, (2005) 'Faster Rubisco is the key to superior nitrogen use efficiency in NADP-ME relative to NAD-ME C4 grasses', Plant Physiology, vol.137, pp 638-650

Pellny T, Ghannoum O, Conroy JP, Schluepmann H, Smeekens S, Andralojc J, Krause K-P, Goddijn O, Paul MJ, (2004) 'Genetic modification of photosynthesis with E. coli genes for trehalose synthesis', Plant Biotechnology Journal, vol.2, pp 71-82

*Siebke K, Ghannoum O, Conroy JP, Badger MR, von Caemmerer S, (2003) 'Photosynthetic oxygen exchange in C4 grasses: the role of oxygen as electron acceptor', Plant, Cell and Environment, vol.26, pp 1963-1972

*Ghannoum O, Conroy JP, Driscoll SP, Paul MJ, Foyer CH, and Lawlor DW, (2003) 'Non-stomatal limitations are responsible for drought-induced photosynthetic inhibition in four C4 grasses', New Phytologist, vol.159, pp 835-844

Siebke K, Ghannoum O, Conroy JP, von Caemmerer S, (2002) 'Elevated CO2 increases the leaf temperature of two glasshouse-grown C4 grasses', Functional Plant Biology, vol.29, pp 1377-1384

*Ghannoum O, von Caemmerer S, Conroy JP, (2002) 'The effect of drought on plant water use efficiency of 9 NAD-ME and 9 NADP-ME C4 grasses', Functional Plant Biology, vol.29, pp 1337-1348

Seneweera SP, Conroy JP, Ishimaru K, Ghannoum O, Okada M, Lieffering M, Kim H-Y, Kobayashi K, (2002) 'Changes in source-sink relations during development influence photosynthetic acclimation of rice to free-air CO2 enrichment (FACE)', Functional Plant Biology, vol.29, pp 945-953

Ghannoum O, von Caemmerer S, Conroy JP, (2001a) 'Carbon and water economy of Australian NAD-ME and NADP-ME C4 grasses', Functional Plant Biology, vol.28, pp 213-223

Ghannoum O, von Caemmerer S, Conroy JP, (2001b) 'Plant water use efficiency of 17 Australian NAD-ME and NADP-ME C4 grasses at ambient and elevated CO2 partial pressure', Functional Plant Biology, vol.28, pp 1207-1217

Seneweera SP, Ghannoum O, Conroy JP, (2001) 'Root and shoot factors contribute to the effect of drought on photosynthesis and growth of the C4 grass Panicum coloratum at elevated CO2 partial pressure', Functional Plant Biology, vol.28, pp 451-460

von Caemmerer S, Ghannoum O, Conroy JP, Clark H, Newton PCD, (2001) 'Photosynthetic responses of temperate species to free air CO2 enrichment (FACE) in a grazed New Zealand pasture', Functional Plant Biology, vol.28, pp 439-450

Ziska LH, Ghannoum O, Baker JT, Conroy J, Bunce JA, Kobayashi K, Okada M, (2001) 'A global perspective of ground level, "ambient" carbon dioxide for assessing the response of plants to atmospheric CO2', Global Change Biology, vol.7, pp 789-796

Ghannoum O, von Caemmerer S, Ziska LH, and Conroy JP, (2000) 'The growth response of C4 plants to rising atmospheric CO2 partial pressure: a reassessment', Plant, Cell and Environment, vol.23, pp 931-942 (Review)

Aben S. Seneweera S. Ghannoum O, Conroy J, (1999) 'Nitrogen requirement for maximum growth and photosynthesis of rice Oryza sativa L. cv Jarrah grown at 36 and 70 Pa CO2', Functional Plant Biology, vol.26, pp 759-766

Howden SM, McKeon GM, Walker L, Carter JO, Conroy JP, Hall WB, Ash AJ, Ghannoum O, (1999) 'Global change impacts on native pasture in south-east Queensland, Australia', Environmental Modelling & Software, vol.14, pp 307-316

Ghannoum O, Conroy JP, (1998) 'N deficiency precludes a growth response to elevated CO2 in C3 and C4 Panicum grasses', Functional Plant Biology, vol.25, pp 627-636

Ghannoum O, Siebke K, von Caemmerer S, Conroy JP, (1998) 'The photosynthesis of young C4 Panicum leaves is not C3-like', Plant, Cell and Environment, vol.9, pp 1123-1131

Seneweera SP, Ghannoum O, Conroy JP, (1998) 'High vapour pressure deficit and low soil water availability enhance shoot growth responses of a C4 grass (Panicum coloratum cv. Bambatsi) to CO2 enrichment' Functional Plant Biology, vol.25, pp 287-292

Ghannoum O, von Caemmerer S, Barlow EWR, Conroy JP, (1997) 'The Effect of CO2 enrichment and irradiance on the growth, morphology and gas exchange of a C3 (Panicum laxum) and a C4 (Panicum antidotale) grass' Functional Plant Biology, vol.24, pp 227-237

Conference Proceedings

Ghannoum O, von Caemmerer S, Conroy JP, (2001) Growth and water use efficiency of NAD-ME and NADP-ME C4 grasses exposed to a drying soil, in: Proceedings of the 12th International Congress on Photosynthesis. (Paper No. S17-006), CSIRO Publishing, Melbourne

Siebke S, Ghannoum O, Conroy JP, von Caemmerer S, (2001) Leaf temperature of C4 grasses is increased in elevated CO2 in a glasshouse, in Proceedings of the 12th International Congress on Photosynthesis. (Paper No. S32-012), CSIRO Publishing, Melbourne