GM trees in US

| 1st November 2007
The US government has given he go-ahead for a test plot of genetically modified (GM) eucalyptus trees in Alabama. For the first time, these trees will be allowed to flower and set seed, opening the door to potential widespread contamination of the American South.

Some of the trees are genetically engineered by biotech firm ArborGen for cold tolerance, others with ‘confidential’ traits. Published articles and industry reports indicate these traits may include the ability to kill insects and reduced lignin. Lignin gives trees strength and enables them to take up water.

The permit for the flowering GM eucalyptus was approved by APHIS (the Animal Plant Health Inspection Service, a sub-department of the US Department of Agriculture). The approval follows APHIS’s grant of non-regulated status for the GM pox-resistant ‘Honeysweet’ plum, which the USDA itself helped develop. Non-regulated status is given on the basis that APHIS has decided that the plant does not present a risk of introduction or dissemination of a plant pest. Deregulation of the GM plum marked the first commercial release of a GM temperate tree in the US. It occurred in spite of the fact public comments against the proposal to deregulate the plum outnumbered those in favour by 100 to 1.

APHIS has also approved the largest-ever release in the US of GM poplars, some modified for reduced stature and light response, others for altered lignin content and others to result in a male-sterile plant.

The raft of approvals confirms the trend in the US regulatory system to approve applications for release without regard for the risks.

As far as eucalyptus is concerned, even to introduce it in its non-GM form could be foolhardy. Eucalyptus is a species of the tropics and subtropics, and is not native to the US. In countries where it has been introduced, it has become invasive. The fact some of ArborGen’s GM eucalyptus trees are modified to be cold-tolerant will extend their ability to colonise. There is no way of knowing how this and the eucalyptus’s other GM traits (which ArborGen will not reveal) may impact forests and wildlife.

Another problem ignored by APHIS is the risk to people and animals. The Global Justice Ecology Project has uncovered evidence that one eucalyptus species engineered into the GM version is host to a deadly pathogenic fungus, Cryptococcus gattii, which causes fatal fungal meningitis in people and animals that inhale its spores. Cases are increasing worldwide, possibly coinciding with the spread of introduced eucalyptus. Two recent studies show that the fungal human pathogen is common in eucalyptus and that it is endemic in the Northwest US and British Columbia, Canada. APHIS ignored the fact eucalyptus poses a threat. It has dismissed the warnings of scientists such as Dr Joseph Heitman, director of the Center for Microbial Pathogenesis at Duke University Medical Center, North Carolina, and an expert on Cryptococcus, who said, ‘Introducing large numbers of eucalyptus trees in the US has the potential to provide a suitable habitat for Cryptococcus gattii.’

A major reason regulators bow to pressure to commercialise GM trees is that they are claimed to offset carbon emissions and thus qualify for subsidies under the Kyoto Protocol’s Clean Development Mechanism. Rising demand for biofuels has also allowed proponents to rescue GM crops from chronic market failure by promoting them as energy crops. Unfortunately, energy crops, including GM trees, are far from sustainable. The UN is one of several bodies pointing out that the rush to energy crops threatens increased poverty and food shortages.


Earlier this year a UN report said biofuels were not guaranteed to reduce greenhouse gas emissions. Biofuels result in some reductions compared to petroleum fuels, it says, but this is provided there is no clearing of forest or peat that store centuries of carbon. In reality, deforestation is already speeding up in Brazil, Malaysia and Indonesia to make way for palm oil and other plantations to feed the new biodiesel market.

The traits engineered into GM trees bring their own environmental problems. Sterility technology, as used in GM poplars, is designed to make trees male-sterile by making the pollen nonviable. It is promoted as preventing GM contamination of other plants, but is a ‘leaky’ technology that produces some viable pollen. Thus the male sterility trait could spread to non-GM trees, leading to sterile forests.

Bt trees, in which a pesticide is engineered into every cell, are toxic to insects. Evidence is growing that Bt crops are also toxic to non-target organisms, such as animals that graze on them or feed on insects that have ingested the Bt. Bt crops infect soil, too. Trees have life-cycles of 100 years or more, so Bt plantations will be sources of toxicity for years to come.

Low-lignin trees are of particular value to the biofuels industry. Anne Petermann co-director of the Global Justice Ecology Project, says, ‘Cellulose is the material of interest in the manufacture of cellulosic ethanol, and lignin gets in the way, so engineering trees for reduced lignin and more cellulose is of great interest. It’s unlikely that industry would pursue trees for cellulosic ethanol without them being genetically engineered.’

The problem with low-lignin trees is that half their strength has been removed, making them vulnerable to environmental stresses such as pests and high winds. The tendency of GM traits to leak into ecosystems raises the prospect of disastrously weakened forests unable to cope with increasingly extreme weather. Once fallen, such trees decompose more rapidly, returning carbon dioxide to the atmosphere at an accelerated rate.

In spite of the hype surrounding the use of wood for biofuels, the technology does not yet exist to do it efficiently. It probably cannot be done without using GM enzymes. For this reason, the US Department of Energy’s Joint Genome Institute is involved in a project to genetically engineer the enzyme from the gut of a termite to aid the cellulose-digestion process. As Anne Petermann says, ‘Imagine the impact on forests if that got loose.’ When it comes to GM trees, it seems our regulators would prefer not to imagine, or even to exercise common sense.

Clare Robinson is an editor at GM Watch

This article first appeared in the Ecologist November 2007

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