A plant that accumulates and detoxifies arsenic?

7 December 2001

Biologists at the University of Wollongong are hoping that new research into plants could lead to the creation of a new type of plant capable of extracting arsenic from polluted soils.

JieHua Wu, a postgraduate student from the Department of Biological Sciences, has identified enzymes in leaves from a plant that converts arsenic to less toxic organic forms. These enzymes become active after the roots of the plant encounter arsenate. It is hoped this discovery will enable researchers to identify the genes responsible for tolerance to arsenic and genetically engineer them in other plants with fast growing deep roots, which could be used to remedy contaminated soils.

Associate Professor Ross Lilley and Dr Ren Zhang are leading the research group in its goal to create a new plant capable of extracting arsenic from polluted soils and concentrating it in the leaves in a less toxic form. Arsenic-polluted soils, a legacy of mining, industrial, agricultural and ground-water pumping activities, are a major and widespread global toxicity problem. In northern NSW alone there are more than 1,500 old cattle dip sites at which the surrounding soil is contaminated with extremely high arsenic levels. These present a rural pollution problem that has been recognised as urgent by federal and state governments.

Some plants have achieved a degree of resistance to elevated arsenic concentrations in the soil by reduced uptake, while others actually accumulate arsenic.

"Over the last three-years we have been studying a species of bentgrass. It has long been known that this grass grows happily in soil containing arsenic levels lethal to most plants. Moreover this plant actually accumulates arsenic in its leaves to extraordinary levels," Professor Ross Lilley said.

"Practical remediation schemes will require plants with deeper root systems to be discovered or engineered with this arsenic-accumulating capability. The upper parts of these plants could then be harvested and dried, resulting in the removal of arsenic from the soil into a small volume easily disposed of," he said.

For further information contact Associate Professor Ross Lilley on 4221 3431 or email rossl@uow.edu.au