Artificial fortification of Nature

June 2019

One of the first GM 'decontaminations' by activists in the UK was carried out in 1999 when two field trials of 115 GM poplar trees were trashed.

The reasons given for this action were blunt:
"those who are manipulating the DNA of trees using a very powerful but dimly understood technology, show contempt for our planet and the life it supports, including human life".
Media warnings were succinct: GM trees could lead to "a silent spring in the forests of the future".

Until the activists struck, Britain was intent on becoming a world leader in GM trees.

Since then, GM trees for commercial cropping, for example 'arctic' non-browning apples and superfast growing eucalyptus for paper, plastics and biofuel production, have been under development in the UK and around the world [1].  These are intended for confined sites.

The latest GM tree venture to surface was also a British idea and is much more ominous, more contemptuous of Nature and more than ever likely to lead to a "silent spring": a GM forest tree intended specifically to spread freely through the wild.

During the first half of the 20th Century, the American chestnut tree, once a dominant species in North American forests, was decimated by a fungal blight and by logging.

Genetic engineers have created GM American chestnut trees which can limit the spread of the fungus within them and so make the infection less lethal.  The theory is simple: the blight produces an acid which breaks down the tree tissue preparatory to invasion; the GM trees have an artificial gene copied from wheat for an enzyme which denatures the fungal acid and prevents the invasion.  This tactic isn't new, the research goes back twenty years.  It's been tried and found effective in peanuts, soyabeans, canola and poplar trees, but none, it seems, have been found effective enough to be worth commercialising (yet).

If approved for release, GM American chestnut trees are intended to become a dominant species in North American forests, where they pose layer upon layer of concerns.

Trees are very big (they take up lots of space), they grow very slowly and have a very long life-span (they're around a long time); their interactions with the surrounding dynamic ecosystems (climate, air, weather, soil, plants, animals and microbes) are far-reaching, time-dependent and immensely complex.  A technique, like genetic modification, which relies on mass transformations followed by elimination of the vast numbers of failures is not practical in the case of trees. 

Little information about the inserted DNA constructs is available, but we do know that the plant pathogen, Agrobacterium, was used as the vector: this technique is known to cause unintended disruption in the structure and function of the genome.  Repeated back-crossing with non-GM strains for several generations to dilute out the unwanted changes, as can be carried out with GM crop plants, is not possible with trees.

GM trees in confined orchards or stands for fast-cropping don't have to be like their natural ancestors, but the trees proposed for re-population of, and interaction with, the North American forests are going to be very different from the old chestnut trees.

Genetic modification for pathogen resistance in crop plants is proving to have a short shelf-life: successful pathogens have a great capacity to evolve, especially when their hosts' defence mechanisms are simplistic.  Genetic engineers try to get round this using fresh waves of GM traits and stacking the old traits together in one plant.  Given the disparity in generation time of the American chestnut trees (hundreds of years) and blight (weeks), there's no doubt the pathogen will outsmart the genetic engineers and make a come-back in a new form.  Moreover, since the GM trait doesn't kill the fungus but simply limits its spread, it would seem to provide a perfect scenario for evolution.

**Note. Genetic engineers already know that a single artificial gene won't, on its own, be effective in conferring durable blight resistance. They anticipate the need for a suite of genes. One of the American chestnut researchers spells out their plans: "Eventually we hope to fortify American chestnuts with many different genes that confer resistance in distinct ways. Then, even if the fungus evolves new weapons against one of the engineered defences, the trees will not be helpless".
Given a pathogen with a potential to evolve every few weeks, how realistic is this?

The current optimism that the GM technology will work is based on an extrapolation from very young (15-year old) American chestnut trees (which are naturally more resistant to blight because they're young) to older trees with a different (older) physiology, different environmental conditions and, inevitably, an evolved blight to deal with.

No one seems to be considering the health effects of GM chestnuts on potential consumers or of GM pollen on potential air-breathers.  The artificial enzyme breaks the fungal acid down to hydrogen peroxide, an unstable but highly reactive substance damaging to microbes: knock-on effects on gut and surface microflora, both essential to the health of organisms, are not being assessed.

The biggest alarm bell ringing here is that the GM American chestnut tree is clearly being promoted as a test case to sway public opinion towards supporting the use of biotechnology for nature conservation, and pave the way for the introduction of more GMOs.  This was the same PR angle dreamed up by UK genetic engineers to solve what they claimed were 'knee-jerk responses' of conservation groups to the very mention of GM trees.

Regulatory agencies are ill-equipped to evaluate the risks of a GM tree intended for deliberate spread through wild areas. We have minimal knowledge of highly complex and dynamic forest ecosystems, monitoring the GM trees' effects will be impossible, and they will cross national and political boundaries. 

And another thing ...
The profound importance of specific areas and particular trees in many indigenous cultures isn't compatible with biotech forests. With a fungus to blame, no one's talking about the role of excessive logging in removing all the healthiest American chestnut trees in the first place.


It seems the once-mighty American chestnut tree is set to be the golden rice of the forest. Take action to make sure the PR stunt falls flat. Join 'Stop GE Trees' in opposing the approval of the GM American chestnut. Check out

The Campaign to STOP GE Trees is an international alliance of organisations that united in 2004 to stop the release of genetically engineered trees in order to prevent the anticipated ecologically and socially devastating impacts

[1]  GM TREES ON THE MARCH - July 2017

  • Biotechnology for Forest Health: The Test Case of the Genetically Engineered American Chestnut,, 23.04.19
  • Jasper Copping, Bid to plant genetically-modified trees in UK, Telegraph, 9.08.08
Image of chestnuts by Couleur from Pixabay

No comments:

Post a comment

Thanks for your comment. All comments are moderated before they are published.