Associate Professor Chris Cobbett
Reader
Department of Genetics,
The University of Melbourne  

Personal Website address: http://www.genetics.unimelb.edu.au/Cobbett/
Email: ccobbett@unimelb.edu.au

Research Aims

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The Big Question

• understanding the molecular genetic mechanisms for homeostasis of the essential heavy metal, zinc, in plants

The Short-term goals

• characterising the function of P-type ATPase zinc transporters in the plant Arabidopsis thaliana.
• dentification and characterisation of mutants of Arabidopsis affected in zinc homeostasis

Plant Molecular Genetics

Zinc is an essential micronutrient for all organisms. It is an essential component of many enzymes, including RNA polymerase, Cu/Zn superoxide dismutase and carbonic anhydrase, and of numerous transcriptional regulators, such as the ubiquitous zinc-finger proteins. In humans, zinc-deficiency is one of many micronutrient deficiencies prevalent in various regions of the world particularly where diets are largely vegetarian. Mild zinc deficiency is reported to affect growth rates, brain function and vitamin E uptake in humans. For plants themselves, zinc is one of the most widespread micronutrient deficiencies affecting crop and cereal production. In addition, in plants considerable genetic diversity has been identified in zinc-efficiency and zinc accumulation in crops and other species known to hyperaccumulate zinc (and other heavy metals). Consequently, considerable attention is being paid to the development of plant breeds to address nutritional zinc-deficiency and to understand the basis for metal hyperaccumulation in order to further develop plants for the phytoremediation of polluted environments.

An important aspect of understanding zinc-deficiency and zinc hyperaccumulation in plants is to understand the mechanisms for zinc uptake, translocation and homeostasis at the physiological, biochemical and molecular genetic levels. Our approach is to use the model organism, Arabidopsis thaliana, to identify genes and mutants affected in zinc transport and homeostasis and to investigate the physiological and biochemical roles of these genes and their products. Much or our work is focussed on a group of P-type ATPase transport proteins that we have demonstrated are important in zinc translocation in Arabidopsis. In addition, we are investigating possible roles of other transport proteins in zinc homeostasis.

Group (lab) Members (2004)

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Research Fellow

• Dr. Sarah Sherson

Postgraduate Students

• Ms. Narelle Cairns
• Mr. Michael Haydon
• Mr. Dawar Hussain
• Mr. Edwin Wong

Funding

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Current

ARC: DP0343089 2003-2004
Characterisation of heavy metal transport genes in the plant Arabidopsis:
potential roles in metal detoxification and accumulation.

Applications submitted or planned

ARC DP0556747 2005-2007
Mechanisms of zinc transport and homeostasis in the plant, Arabidopsis.

Techniques in the Laboratory

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Currently active

Genetics and molecular biology; measurement of metals in tissues using ICP in collaboration with Prof. Baker (Botany); metal uptake and accumulation.

In development

Confocal microscopy; in situ hybridisation

Main areas of expertise

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Top three areas of knowledge

1. Plant heavy metal detoxification
2. Plant essential heavy metal homeostasis
3. Arabidopsis molecular genetics

 

Top three technical skills

1. Genetics - isolation and genetic characterisation of mutants
2. Physiology of metal uptake and accumulation
3. Heterologous expression of plant genes in yeast

Publications - Last 5 Years

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• Hussain D, Haydon MJ, Wang Y, Wong E, Sherson SM, Camakaris J, Harper, JF, Cobbett CS. (2004) P-type ATPase heavy metal transporters with roles in essential zinc metabolism in Arabidopsis. Plant Cell in Press

• Cobbett CS, Hussain D, Haydon MJ. (2003) Structural and functional relationships between type 1B heavy metal-transporting P-type ATPases in Arabidopsis. New Phytologist 159: 315-321.

• Tan-Kristanto A, Hoffmann A, Woods R, Batterham P, Cobbett, C, Sinclair C (2003) Translational asymmetry as a sensitive indicator of cadmium stress in plants: a laboratory test with wild-type and mutant Arabidopsis thaliana. New Phytologist 159: 471-477.

• Cobbett CS (2003) Metals and Plants. Model systems and hyper-accumulator species. New Phytologist 159: 289-293 (2003).

• Heiss S, Wachter A, Bogs J, Cobbett C, Rausch T (2003) Phytochelatin synthase (PCS) protein is induced in Brassica juncea leaves after prolonged Cd exposure. J. Experimental Botany 54: 1833-1839.

• Fulton L, Cobbett CS (2003) Two L-arabinofuranosidase genes in Arabidopsis thaliana are differentially expressed during vegetative growth, flower development and in abscission zones. J. Experimental Botany 54: 2467-2477.

• Cobbett CS (2003) Metallothioneins and phytochelatins; the sulfur-containing, metal-binding ligands of plants. In, Sulphur In Plants. Eds. Y.P. Abrol, A. Ahmad. Kluwer Academic Publishers, Dordrecht/Boston/London. pp. 177-188.

• Sanita di Toppi L, Gremigni P, Pawlik-Skowroska B, Prasad MNV, Cobbett CS (2003) Response to heavy metals in plants: a molecular approach. In Abiotic Stresses in Plants. Eds. L. Sanita di Toppi, B. Pawlik-Skowroska. Kluwer Academic Publishers, Dordrecht .

• Cobbett CS (2003) Genetic and molecular analysis of phytochelatin biosynthesis, regulation and function. In, Sulfur Transport and Assimilation in Plants. Eds. J.-C. Davidian, D. Grill, L.J. de Kok, I. Stulen, M.J. Hawksford, E. Schnug, H. Rennenberg. Backhuys Publishers, Leiden . pp. 69-77.

• Maughan, SC, Cobbett, CS. (2003) Methionine sufoximine, an alternative selection for the bar marker in plants. J. Biotechnology 102: 125-128.

• Cobbett, CS, Goldsborough, PB. (2002) Phytochelatins and Metallothioneins: Roles in Heavy metal detoxification and homeostasis. Annu. Rev. Plant Biol. 53: 159-182.

• Cobbett, CS, Meagher, RB. (2002) Arabidopsis and the Genetic Potential for the Phytoremediation of Toxic Elemental and Organic Pollutants. The Arabidopsis Book, eds. C.R. Somerville and E.M. Meyerowitz, American Society of Plant Biologists, Rockville, MD, doi/10.1199/tab.0032 http://www.aspb.org/publications/arabidopsis/ - this publication is only available as an on-line text.

• Cobbett, CS.(2001) Heavy metal detoxification in plants: Phytochelatins: biosynthesis and function. IUBMB Life 51: 183-188.

• Cobbett, CS.(2000) Heavy metal detoxification in plants: Phytochelatins: biosynthesis and function. Australian Biochemist 31: 16-19.

• Cobbett CS, Goldsbrough PB (2000) Mechanisms of metal resistance: metallothioneins and phytochelatins. In, Phytoremediation of toxic metals: using plants to clean-up the environment, Eds. Ensley BD, Raskin I, John Wiley & Sons, New York, USA. 247-269.

• Cobbett, CS (2000) Phytochelatins and their roles in heavy metal detoxification. Plant Physiol. 123: 825-832.

• Cobbett, CS (2000) Phytochelatins and heavy metal tolerance in plants. Current Opinion in Plant Biol. 3: 211-216.

• Vernoux T, Wilson RC, Seeley KA, Reichheld J-P, Muroy S, Maughan S, Cobbett CS, Van Montagu M, Inzé D, May MJ, Sung ZR. (2000) The ROOT MERISTEMLESS1/CADMIUM SENSITIVE2 gene defines a glutathione-dependent pathway involved in initiation and maintenance of cell division during postembryonic root development. Plant Cell 12: 97-109.

• Cobbett CS (1999) A family of phytochelatin synthase genes in plant, fungal and animal species. Trends Plant Sci. 4: 335-337.

• Ha S-B, Smith AP, Howden R, Dietrich WM, Bugg S, O'Connell MJ, Goldsbrough PB, Cobbett CS. (1999) Phytochelatin synthase genes from Arabidopsis and the yeast, Schizosaccharomyces pombe. Plant Cell 11: 1153-1164.

• Sherson S, Gy I, Medd J, Schmidt R, Dean C, Kreis M, Lecharny A, Cobbett C (1999) The arabinose kinase, ARA1, gene of Arabidopsis is a novel member of the galactokinase gene family. Plant Molec. Biol. 39: 1003-1012.