Dr Andrew Merchant

Summary

Understanding how plants cope with environmental change is vital to addressing future global challenges. From food to fuel, climate to conservation, plant resilience plays a central role in ecosystem processes. With a focus on plant function, I am interested in expanding our knowledge and developing tools for the management of plant and ecosystem health.

Research interests

Plant sciences have an enormous array of analytical capabilities spread across a range of disciplines. I enjoy pursuing focused research questions utilizing these capabilities. Below is a list of current major projects. I value questions or comments and can be contacted via .

• Metabolite pools and their implications for plant responses to global change (ARC Discovery)
  Soluble carbon is a major interface between plant function and the environment. This project seeks to characterise how Australian trees alter the allocation of resources to cope with environmental change.
• Chemical markers for stress tolerance – carbon partitioning among metabolite pools (WUN)
  Sponsored by the World Universities Network, this project seeks to develop a better understanding of soluble carbon partitioning in crop plants by an effective combination of chemical and molecular approaches.
• Correction of water and nutrient deficiencies in eucalypts via phloem derived diagnostics (ARC linkage)
  Using revised techniques for the harvesting and analysis of phloem sap, we are developing “phloem sap derived diagnostic tests” for plant water and nutrient status. Offering considerable promise for landscape managers and plant scientists, these rapid, low cost tools improve our ability to address plant and ecosystem scale environmental problems.
• Novel markers for heat and light stress in Australian trees (DAFF)
  Under conditions of resource limitation, plants struggle to cope with light and temperatures that affect tissue growth and survival. This project seeks to determine the roles of cyclic sugar alcohols (cyclitols) in Australian tree species under stressful conditions. The role of cyclitols in maintaining cellular function holds great promise as a molecular selective trait.

Strong, ongoing national and international collaborative links are a valuable component of my research. Using new technologies in analytical chemistry that span molecular, chemical and physiological disciplines, I seek to develop an understanding of chemically based traits for plant adaption to changes in resource availability. To date, this work has characterised distinct geographical and evolutionary patterns in stress metabolites of Australian tree species that have broad implications for ecological, chemical, physiological and evolutionary studies.

With particular focus on soluble carbon and long distance signaling, my ongoing projects study a range of processes that occur in plant tissues and how they are able to mitigate stressful conditions. As one example, I am investigating the roles that cyclic sugar alcohols play in stress tolerance across a range of plant species. Among many potential functions, we have found that these small, soluble compounds act in regulating cellular water status and correlate strongly with the stabilization of plant photosynthetic apparatus at high temperatures.

More recently I have been investigating the use of phloem exudates (sap) as measures of plant physiological and nutritional status. With focus on carbon acquisition, nutrient supply, long distance hormonal and antioxidant signaling, we have developed chemical and stable isotope based diagnostic assessments of plant water and nutrient supply.

I am now expanding the applications of phloem derived diagnostics and soluble metabolite analysis to investigate soluble carbon allocation and stress metabolism among an array common crop plants (including woody crops). In the future I hope to develop this work to address the effects of global change factors on food security and conservation.

Background

Andrew Merchant completed his PhD thesis at the University of Melbourne in 2005 investigating the chemical and physiological adaptation of Eucalyptus species to the effects of salinity and drought. Since then, this work has expanded to encompass a broader range of Australian plant species as well as the multifaceted effects of plant stress.

From 2006 to 2008 Andrew worked as a postdoctoral scientist at the University of New South Wales developing phloem derived diagnostic tools for plant health. In 2007 he was awarded a federal Department of Agriculture, Forestry and Fisheries Innovation Award for his work on cyclic sugar alcohols and their role in mitigating stressful conditions in tree and crop species.

He was appointed as a lecturer in Agroforestry at the University of Sydney in September 2008 and will commence an Australian Research Council Postdoctoral Fellowship in 2009.

Recent publications

• MERCHANT A., Wild B., Richter A., Bellot S., Adams M.A. & Dreyer E., (2011) Compound-specific differences in ¹³C of soluble carbohydrates in leaves and phloem of 6 month old Eucalyptus globulus (Labill). Plant Cell and Environment (in press).
• Dempsey R.W., MERCHANT A. & Tausz M. (2011) Increasing leaf glutathione through stem feeding does not acclimate Eucalyptus camaldulensis seedlings towards high-light stress. Acta Physiologiae Plantarum, 33, 221-225.
• MERCHANT A., Peuke A.D., Keitel C., Macfarlane C., Warren C. & Adams M.A. (2010) Phloem sap and leaf δ¹³C, carbohydrates and amino acid concentrations in Eucalyptus globulus change systematically according to flooding and water deficit treatment. Journal of Experimental Botany, 61, 1785-1793.
• MERCHANT A., Tausz M., Keitel C. & Adams M.A. (2010) Relations of sugar composition and δ¹³C in phloem sap to growth and physiological performance of Eucalyptus globulus (Labill) Plant Cell and Environment, 33, 1361-1368.
• Volkova L., Bennett L.T., MERCHANT A. & Tausz M. (2010) Shade does not ameliorate drought effects on the tree fern species Dicksonia antarctica and Cyathea australis. Trees-Structure and Function, 24, 351-362.
• MERCHANT A, Arndt S K, Rowell D M, Posch S, Callister A, Tausz M and Adams M A (2010), Seasonal changes in carbohydrates, cyclitols, and water relations of 3 field grown Eucalyptus species from contrasting taxonomy on a common site. Annals of Forest Science 67, 104-110.
• MERCHANT A, Arndt S K, Callister A, Adams M A. (2009) How does Eucalyptus leptophylla (F. Muell) cope with naturally saline conditions near the ‘Pink Lakes’, north-west Victoria. Environmental and Experimental Botany. 65: 2-3 96-303.
• Tausz M, Merchant A, Kruse J, Samsa G, Adams M A. (2008) Estimation of drought related limitations to mid-rotation aged plantation grown Eucalyptus globulus by phloem sap analysis. Forest Ecology and Management 256, 844-848.
• Arndt S, Livesley S, Merchant A, Bleby T, Grierson P (2008). Quercitol and osmotic adaptation of field grown Eucalyptus under seasonal drought stress. Plant Cell and Environment 31, 915-924.
• Kahmen A, Simonin K, Tu K, Merchant A, Callister A, Dawson T, Arndt S. (2008). Physiological and morphological effects on leaf water Δ¹⁸O enrichment in different Eucalyptus species Plant Cell and Environment 31, 738-751.
• Callister A, Arndt S, Ades P, Merchant A, Rowell D, Adams M. (2008) Leaf osmotic potential of Eucalyptus hybrids respond differently to freezing and drought stresses and with little clonal variation Tree Physiology 28, 1297-1304.
• Merchant A, Ladiges P, Adams M A. (2007). Sub-generic taxonomic distribution of the cyclitol quercitol provides putative links with aridity tolerance in species of Eucalyptus. Global Ecology and Biogeography 16, 810-819.
• Merchant A, Callister A, Arndt S K, Adams M A. (2007). Contrasting physiological responses of six Eucalyptus species to water deficit. Annals of Botany 100, 1507 - 1515.
• Merchant A, Arndt S K, Tausz M, Adams M A (2006) Metabolite profiling suggests contrasting physiological responses to drought in 13 Eucalyptus species. Plant Cell and Environment 29, 2017-2029.
• Merchant A, Richter A, Popp M, Adams M A (2006). A metabolite approach provides functional links among eucalypt taxonomy, physiology and evolution. Phytochemistry 67, 402-408.
• Merchant A, Adams M A. (2005). Stable osmotica in Eucalyptus spathulata – responses to salt and water deficit stress. Functional Plant Biology 32, 9, 797-805.

Contact

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