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Therese Forsberg
Småbrukaren Nr 3 höst 2011

This year genetically modified (GM) hybrid aspen and fruit trees are growing on 3,8 ha in Sweden. Proponents believe that GMO-trees are part of the solution to the problem of a growing population. Critics are concerned about the negative consequences for the ecosystem and the risks for human and animal health.

The field trials with GMO trees include hybrid aspen and apple and pear trees. The aspen have been modified to have higher growth rate and to be drought resistant.1 The fruit trees have been modified to have a stronger root system. Conventionally bred varieties are then grafted on to the rootstem. In order to stop the spread of these GMO genes the authorisation allows no rootshoots, flowers or fruits to develop on the GMO plants. The hybrid aspen is not allowed to flower in order to prevent the spread of genetic material. Despite this there is a risk according to Ann Charlotte Berntsson of Sotenas Beekeepers Association. “I am critical of these trials. Even if the trees are not allowed to flower bees can in principal suck the leaf juice and spread the genes in this way.”

Wants to test the safety

Because of the risk for the spread of genetic material Ann-Charlotte Berntsson wants the trees to be tested for food safety aspects. Through bees, pollen containing genetic material could end up in honey. Today no food safety tests are done because trees are not considered to be used for food directly. If the tree should flower by mistake then the risk for spread increases greatly.

“What happens then if these trees are approved for the market? In small field trials researchers can perhaps ensure that no trees flower (and if they do remove the flowers) but if they are planted on a larger scale who can check if they flower then?” asks Ann-Charlotte Berntsson. Flowering would increase the risk of spread to their wild relatives.

Can spread long distances

Joakim Hjältén is a professor at the Department of Wildlife, Fish and Environmental Studies at the Swedish University of Agricultural Sciences (SLU) in Umeå. He has done research on the ecological risks with genetically engineered trees. His research shows that in general the spread of genetic material can differ greatly from one variety to another. “But some can spread long distances under good conditions”.

Field studies combined with modeling for how genes spread among different stands of poplar trees show that after 25 – 50 years the modified genes from GMO-trees, if they flower, will be present in at least 1% of the other stands. If it stops at 1% or increases depends on whether or not the altered gene gives the tree a competitive advantage. In the application for authorisation to carry out GMO field trials the Swedish Board of Agriculture noted that the GMO-tree in question had competitive advantages compared to its wild relatives. This means that, according to the study findings, the frequency of the altered genes will continue to increase in nature.

“It is only a technique”

Mats Johnson is CEO of the company Swedtree Technologies that works with, among other things, transgenic trees. He thinks that it is wrong to focus on the GMO-technology per se and that the risks are small because they are following a scientific method and the existing rules.

“In technical terms, GMO is only a technology that can be applied in different ways. It is what is done with the technology that is crucial. GMO is a way of plant breeding that is knowledge-based.2  In our trials we mainly use the trees own genes and in some cases corresponding genes from cress”, he says.

Genes from bacteria that are resistant to the antibiotics canamycin and hygromycin are also used. There is an ongoing debate as to whether their use can increase the risk for multi-resistant bacteria and be a threaten to human health.

See no great risks

The Swedish Gene Technology Advisory Board (SGTAD) has in a policy decision declared that they do not see any risk that antibiotic resistance can spread through use of antibiotic resistant bacteria in GMOs. Laboratory experiments have shown that horizontal gene transfer3, can take place. The Board has drawn the conclusion that this seldom happens in nature. Ann-Charlotte Berntsson believes that because so little research has been done on the horizontal transfer of genes, there are risks with increased antibiotics resistance and other foreign genes in our food.

Wants studies on bees

In the bee’s honey stomach there are on average 13 million beneficial lactic acid bacteria. This honey stomach is completely separate from the bees’ digestive track and is in principal a chamber for bacteria production, according to Ann-Charlotte Berntsson.

She explains that the pollen and nectar is preserved with the help of the bacteria flora in the honey stomach. Ann-Charlotte Berntsson thinks there is a  need for studies on whether horizontal gene transfer occurs in the honey stomach.

“It is well known lactic and bifido bacteria readily transfer the same kind of microrganisms that are used in GMO-plants so you can wonder why no studies are carried out”, she says.

There are examples where researchers have seen horizontal gene transfer from food containing GM-soybean to colon bacteria in a colostomy bag. The researchers who carried out the study think, despite their findings, that it probably doesn’t mean that this will be problematic for human health.

However they do think that it is necessary to take into account the fact that GMO-sequences can survive passage through the small intestines.

No comments

Mats Johnson has no comments concerning the risk that bees can spread genetic material by sucking plant juices. “I have no idea how it works and don’t want to comment. But the problem of co-existence must first be solved within agriculture. It has completely different dimensions there,” he said.

New jurisprudence expected

The spread of GMO-sequences to honey has been dealt with in a German case in the EU court and everything suggests that the new jurisprudence in the EU will mean that bee-keepers may not sell their honey as food if it contains GMO.4

“That Mats Johnson can consider releasing GMOs in nature that are not approved for food  consumption despite the fact that he knows that they will end up in our food, is scandalous,” says Ann-Charlotte Bernatson.

Only for research purposes

The trials the company is carrying out with GM-trees are only for research purposes, says Mats Johnson. If there will be any marketable products in the future depends on the results of the research, he says.

Not specific for GMO

Professor Joakim Hjältén thinks that the consequences from growing GM-trees for a forest production system  are not limited specifically to their being GMO. Rather it’s a question of how faster growing trees will influence the ecosystem. This is also relevant for exotic tree species or conventionally bred trees with specific characteristics.It can, for example, be a question of how the process of decomposition and the quality of litter is affected.

“We need to discuss what alternatives there are to conventional methods. I believe that it will be necessary to intensify forest production in order to reduce our need for oil and to increase our production of forest products,” says Joakim Hjältén.

There are different strategies

The Swedish model has been to take environmental consideration generally during harvest in order to keep as high biological diversity as possible in the productive forests. At the same time small areas have been protected compared to many other countries.

Another strategy is to have a more intensive production on certain areas and have larger areas that are protected. What is most effective from a production and environmental perspective is continuously being asked.

National agreement is needed

“My personal opinion is that it is probably better to have a larger area reserved. I’m not saying that this is what I want, but that it is time to think through the alternatives. Based on our knowledge today, it is difficult to give clear recommendations. It is a gamble. Politicians and forest industry interests want a clear answer now. As a researcher, I can say that national agreement on these issues is required,” says Joakim Hjältén.

The system’s susceptibility/resilience

Another question concerns the resilience of a forest production system with GMO-trees. The risk with having a narrow genetic base for all the individuals in the plantation is that the trees are more susceptible to illness and have more trouble adapting to climate change for example.

“This has nothing to do with GMO”, says Mats Johnson. “Rather it has to do with how many clones we work with. There are models based on statistical calculations that tell us how many we need. Also it depends on how large an area is to be grown. We have strategies developed for plantation and clone forest production to avoid such problems.”

More raw material is needed

Mats Johnson thinks that the underlying problem that has created the need for GMO-trees is  population growth and the need of renewable raw material for energy and commodities.

“We have the land we have and we must produce more volume per hectare if we are to manage. Therefore we must use the knowledge and technology we have,
but of course in a sustainable way.”

Ann-Charlotte Berntsson doesn’t think that GMO is a sustainable solution to the problems Mats Johnson mentioned. It is not in line with the precautionary principle to release GMOs in nature.5

The economic interests that the forest industry has in GMO technology is also of concern to her.

“I am a forest owner myself and know how difficult it is already today to get a hold of the kind of trees I want. I want to plant larch but there are only hybrid larches available for purchase. It is difficult to buy plants that are not clones or hybrids especially of minor species. What would happen if the forest industry decides that it is GMO-trees that are our future? They would develop and patent their GMO-plants from our wild species and lock away the real thing in Svalbard. We don’t have the keys to that global seed vault. Imagine if diseases, blockades or other such events stopped our supply of seeds and plants? How long would  we be able to manage then?” wonders Ann-Charlotte Berntsson.