GM trees most poplar choice for metals remediation

Genetically modified poplar trees could offer the best hope for remediation of soils contaminated with high levels of heavy metals such as zinc.

Poplar trees are already known to be good candidates for bio-remediation because of their fast growth rates and large biomass production. They also have an extensive root system which ensures a large uptake of the soil water containing the pollutants.

Their fast growth makes them ideal for use in industries such as paper and biomass, maximising their commercial potential on contaminated sites.

Several other inorganic pollutants can be taken up by poplars, including cadmium and mercury, yet their tolerance is restricted because they can only remediate a certain amount.

Now, scientists from the Plant Protection Institute at the Hungarian Academy of Sciences in Budapest have found that trees with an increased amount of an enzyme called y-glutamylcysteine-synthetase (y-ECS) take up more cadmium than plants with less of the enzyme.

They then used this knowledge to conduct an experiment using transgenic poplars that significantly overproduced the y-ECS enzyme and examined the uptake of heavy metals.

The experiments found that the GM trees accumulated more of the metals than the others. The GM-poplars were found to be more tolerant to zinc exposure than their non-GM counterparts and therefore, the scientists claim, more suitable for bio-remediation purposes.

The scientists, led by Dr Tamas Komives, said there was huge potential for these trees in phyto-remediation projects. His team has applied for permission to plant the stress tolerant GM trees at an industrial waste site where the non-GM poplar trees are suffering due to the high levels of toxicity.

Last week, edie news reported that researchers in Scottish Universities had found that fungi living on the roots of Scots pine trees can make powerful acids to help dissolve pollutants making them easier for take up by the plants (see related story).

David Hopkins



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