Professor Stephen Powles
Professor and Director, WAHRI
WAHRI, School of Plant Biology,
University of Western Australia ,
35 Stirling Highway , Crawley 6009

Personal website address: http://wahri.agric.uwa.edu.au
Email Address: spowles@agric.uwa.edu.au

Research Aims

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The Big Question

Research is focused on understanding the population genetics/dynamics, the molecular and biochemical basis and the management of evolved resistance to herbicides in plants (weedy species) that are under selection pressure from herbicides. Research is focused on the annual grass species Lolium rigidum because this species in Australia has developed resistance faster and to more herbicides than any other cases of resistance, worldwide. Substantial work is also occurring with the economically important dicot Raphanus raphanistrum .

The Short-term Goals

Elucidating the population genetics, mechanism and agro-ecological fitness of resistance to the important herbicides glyphosate and paraquat in Lolium ridigum is a major short term goal. Identifying the biochemical basis of multiple resistance in Raphanus raphanistrum is also a focus. The development of population dynamics and genetics models to understand, predict and manage resistance is a priority.

Laboratory Members (and areas of research)

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Postdoctoral Fellows

• Dr. Paul Neve Resistance population genetics and dynamics. Modelling.
• Dr. Xiao Qi Zhang Molecular and biochemical basis of herbicide resistance.
• Dr. Qin Yu . Molecular and biochemical basis of paraquat resistance.
• Dr. Michael Walsh . Management of herbicide resistance.

PhD students

• Mr. Martin Vila Aiub. Agro-ecological fitness of herbicide resistant populations.
• Mr. Shane Friesen. Biochemical and molecular basis of multiple resistance in Raphanus raphanistrum.

Research Officer

• Ms. Mechelle Owen . Surveys and screening for herbicide resistance.

Funding

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Currently Active

• Grains Research & Development Corporation. $400,000 per annum.

Applications Submitted or planned

Techniques in the Laboratory

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Currently Active

• Precision application of herbicides.
• 14C radiolabelled herbicide studies of uptake, translocation, metabolism.
• Enzyme extraction, purification and assay.
• Molecular identification of mutations.
• Plant competition studies.

In Development

Main areas of Expertise

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Top three :

Areas of Knowledge

1. Biochemical basis of herbicide resistance in plants.
2. Plant evolutionary population genetics and dynamics.
3. Crop Production and weed management.

Technical Skills

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Most significant contributions to herbicide resistance research field.

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Our herbicide resistance team has published 80 research papers, 15 book chapters, two major reviews and two resistance books. The quality and volume of our Australian work shapes international herbicide resistance research and has a major impact on the agrichemical industry. At the fundamental level our work elucidates biochemical resistance mechanisms, inheritance patterns and nucleotide substitutions endowing resistance across many herbicide chemistries. Our applied studies on the agro-ecology and agronomic management of herbicide resistance has fundamental and applied outcomes encapsulated in population genetics and population dynamic simulation models for use in resistance management by the cropping industry and the international agrichemical industry. Tangible international and national recognition include S. Powles achieving ISI most highly cited scientist (ISIhighlycited.com) and election to the Australian Academy Technological Sciences & Engineering, and 2003 award of the Centenary Medal.

Other evidence of impact and contributions to the field

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Quantifiable evidence of the impact and contributions made to herbicide resistance/plant science research are the scientific publications produced. Commencing in 1986, and until December 2003, our herbicide resistance research team have published:

 

(i) Research papers in international journals

a) Evolved resistance to glyphosate Seven papers published.
b) Evolved resistance to ACCase herbicides. Nineteen papers published.
c) Evolved resistance to ALS herbicides. Ten papers published.
d) Evolved resistance to PSII herbicides. Six papers published.
e) Evolved multiple resistance. Six papers published.
f) Evolved resistance to paraquat. Eighteen papers published.
g) Resistance management/modeling. Ten papers published.
h) Gene flow in GM herbicide resistant crops. Three papers published .

Total Seventy Nine

(ii) Invited chapters in books & reviews

Fifteen chapters and two reviews have been published.

(iii) Two Books co-edited

1994. Herbicide Resistance in Plants. Edited S.B. Powles & J.A.M. Holtum, Lewis/CRC Press.

2001. Herbicide Resistance & World Grains. Edited S.B. Powles & D.L. Shaner, CRC Press.

The Institute for Scientific Information (ISI) in Philadelphia , USA have created the ISI Highly Cited Scientist category, recognising the 100 most highly cited international scientists in each of a range of research fields (ISIhighlycited.com). This is determined by quantifying the frequency of citation of an individuals research, by other authors in publishing their own scientific papers. In 2002, ISI placed Powles in the top 100 scientists worldwide for citations in the category Plant & Animal Sciences.

Awards

• 1997 - I was elected International Honorary Fellow of the Weed Science Society of America, in recognition of my research achievements in herbicide resistance, especially the elucidation of multiple resistance. I am the only Australian to have received this award.
• 1999 - I was elected as a Fellow of the Australian Academy of Technological Sciences & Engineering, in recognition of contribution to plant production.
• 2002 - Institute for Scientific Information, Philadelphia, USA. Highly cited scientist - Plant Science category.
• 2003 - I was awarded an Australian Centenary Medal for services to plant culture and production.

Invited plenary addresses at international conferences

I am regularly invited to be the plenary speaker and session organizer (herbicide resistance) at international conferences (I decline some invitations and suggest attendance of one of my postdoctoral colleagues). During the ten years 1993-2003 I delivered seventeen invited plenary addresses at international conferences.

Publications - Last 5 Years

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Books

• Herbicide Resistance and World Grains. Editors: Stephen B Powles & Dale L Shaner. CRC Press. 2001.

Book Chapters

• Powles, S.B. and Preston, C. (1999) Herbicide Resistance: A case of rapid evolution. In: Plants in Action: Adaptation in Nature, Performance in Cultivation. Ed. B. Atwell, P. Kriedemann and C. Turnbull. Pub: Macmillan Education Australia. pp. 607-613.

• Rieger, M.A., Preston, C., Potter, T., Powles, S.B. (1999) Gene flow from transgenic canola to wild radish - a model system to determine the risks. In: Lutman, P.J.W. (Ed) Gene Flow and Agriculture: Relevance for Transgenic Crops. British Crop Protection Council, pp. 131-136

• Powles, S.B. and Bowran. D.G. (2000) Crop Weed Management Systems. In: Australian Weed Management Systems. Ed. B. Sindel. Publishers: R.G. & F.J. Richardson. pp. 287-306.

• Preston, C. and Powles, S.B. (2002) Mechanisms of multiple herbicide resistance in Lolium rigidum . In: Agrochemical Resistance: Extent, Mechanism & Detection.. Eds. J.M. Clark & I. Yamaguchi, Oxford University Press. pp. 150-160

Journal Articles

• Walsh, M.J., Powles, S.B ., Beard, B., Parkin, B.T., Porter, S. (2004) Multiple herbicide resistance across four modes of action in wild radish ( Raphanus raphanistrum L.) Weed Science. 52: 287-306.

• Soar, C.J., Karotam, J., Preston, C., Powles, S.B . (2003) Reduced paraquat translocation in paraquat resistant Arctotheca calendula is a consequence of the primary resistance mechanism not the cause. Pesticide Biochemistry & Physiology, 76, 91-98.

• Monjardino, M., Pannell, D.J., Powles, S.B. (2003) Multi-species RIM: A bio-economic model for integrated management of Lolium rigidum and Raphanus raphanistrum in Australian cropping. Weed Science, 51, 798-809.

• Pannell, D.J., Stewart, V., Monjardino, M., Bennett, A., Schmidt, C., Powles, S.B . (2003) RIM- A bioeconomic model for ryegrass ( Lolium rigidum ) management in Australian cropping. Agricultural Systems.

• Neve, P., Diggle, A.J., Smith, F.P., Powles, S.B . (2003) Simulating evolution of glyphosate resistance in Lolium rigidum . I. Population biology of a rare resistance trait. Weed Research 43: 404-417.

• Lorraine-Colwill, D.F., Powles, S.B., Hawkes, T.R., Hollinshead, P.H., Warner, S.A.J., Preston, C. (2003) Differential glyphosate translocation in a resistant Lolium rigidum population. Pesticide Biochemistry and Physiology, 74, 62-74.

• Yu, Q,. Xhang, X Q., Hashem, A., Walsh, M.J., Powles, S.B . (2003) ALS gene proline (197) mutations confer ALS herbicide resistance in eight separated wild radish ( Raphanus raphanistrum ) populations. Weed Science. 51, 831-838.

• Yu, Q., Friesen, S., Zhang, X., Powles, S.B . (2003) Tolerance to acetolactate synthase and acetyl-coenzyme A carboxylase inhibiting herbicides in Vulpia bromoides is conferred by two co-existing resistance mechanisms. Pesticide Biochemistry and Physiology, 78, 21-30.

• Powles, S.B . (2003) My View: Will glyphosate continue to aid world food production?

• Weed Science, 51: 471.

• Delye, C., Xhang, X., Chalopin, C., Michel, S., Powles, S.B . (2003). An isoleucine residue within the carboxyl-transferase domain of multidomain Acetyl-Coenzyme A Carboxylase is a major determinant of sensitivity to aryloxyphenoxypropionate inhibitors but not to cyclohexanedione inhibitors. Plant Physiology. 132, 1716-1723.

• Neve, P, Diggle, A.J., Smith, F.P., Powles, S.B . (2003). Simulating evolution of glyphosate resistance in Lolium rigidum . II. Past, present and future glyphosate use in Australian cropping. Weed Research 43: 418-427.

• Preston, C., Powles, S.B . (2002) Evolution of herbicide resistance in weeds: Initial frequency of target site-based resistance to acetolactate synthase-inhibiting herbicides in Lolium rigidum . Heredity, 88, 8-13.

• Llewellyn, R.S., Lindner, R.K., Pannell, D., Powles, S.B . (2002). Resistance and the herbicide resource: Perceptions of Western Australian grain growers. Crop Protection. 21, 1067-1074.

• Rieger, M.A., Lamond, M., Preston, C., Powles, S.B ., Roush, R.T. (2002). Pollen-mediated movement of herbicide resistance between commercial canola fields. Science. 296 (5577), 2386-2388.

• Walsh, M.J., Duane, R.D., Powles, S.B. (2001) High frequency of chlorsulfuron resistant wild radish ( Raphanus raphanistrum L.) populations across the Western Australian wheatbelt. Weed Technology. 15, 199-203.

• Hashem, A., Dhammu, H.S., Powles, S.B ., Bowran, D.G., Piper, T.J., Cheam, A.H. (2001) Triazine resistance in a biotype of Raphanus raphanistrum in Australia. Weed Technology. 15, 636-641.

• Hole, SJW., McClure, NC., Powles, SB . (2001) Persistence and management of enhanced bio degradation in soil. Weed Research, 41, 341-349.

• Hole, S.J.W., McClure, NC., Powles, SB . (2001) Rapid degradation of carbetamide upon repeated application to Australian soils. Soil Biology & Biochemistry, 33, 739-745.

• Lorraine-Colwill, D.F., Powles, S.B ., Hawkes T.T., Preston, C. (2001) Inheritance of evolved glyphosate resistance in Lolium rigidum . Theoretical & Applied Genetics. 102, 545-550.

• Rieger, M.A., Potter, T.D., Preston, C., Powles, S.B . (2001) Hybridisation between Brassica napus L. and Raphanus raphanistrum L. under agronomic field conditions. Theoretical & Applied Genetics. 103, 555-560.

• Llewellyn, R., Powles, S.B . (2001) High levels of herbicide resistance in rigid ryegrass ( Lolium rigidum ) across the Western Australian wheatbelt. Weed Technology, 15, 242-248

• Matthews, N., Powles, S. B ., Preston, C. (2000) Mechanisms of resistance to acetyl-coenzyme A carboxylase-inhibiting herbicides in a Hordeum leporinum population. Pest Management Science. 56, 441-447.

• Boutsalis, P., Karotam, J., Powles, S.B . (1999) Molecular basis of resistance to acetolactate synthase-inhibiting herbicides in Sisymbrium orientale and Brassica tournefortii . Pesticide Sci., 55, 507-516.

• Tardif, F.J., Powles, S.B . (1999) Effect of malathion on resistance to soil-applied herbicides in a population of rigid ryegrass ( Lolium rigidum ). Weed Science, 47, 258-261.

• Rieger, M.A., Preston, C., Powles, S.B . (1999) Risks of gene flow from transgenic herbicide-resistant canola ( Brassica napus ) to weedy relatives in southern Australian cropping systems.

• Aust. J. Agric. Res. 50, 115-128.

• Lorraine-Colwill, DF., Hawkes, TR., Williams, PH., Warner, SJ., Sutton, PB., Powles, SB ., Preston, C. (1999) Resistance to glyphosate in Lolium rigidum . Pesticide Science, 55, 486-503.