28 October 2015

New routines rather than changed genes behind GM effect

Genetically modified plants and animals have no direct effects on ecosystems. A literature review carried out by Mistra Biotech shows this. But since they offer farmers new methods of cultivating and working the soil, GM crops can have indirect effects.

Genetically modified organisms (GMOs) have been spread and used in farming for nearly three decades, especially in North America and Asia. Many individual studies have looked at how GMOs affect individual insect species in the natural environment, or particular types of microorganism. On the other hand, knowledge of systemic effects to date has been limited, relates Anna-Karin Kolseth, a plant ecologist at the Swedish University of Agricultural Sciences (SLU) in Uppsala.

‘How do GMOs actually function in our cultivation systems? Do they destroy any agricultural opportunities in the future? We know extremely little about their environmental impact and, for instance, how yield is affected.’

A group of researchers with backgrounds in ecology, microbiology and physiology have tried to summarise what existing knowledge there is. The new study, published in the journal Agriculture, Ecosystems and Environment, is the work of researchers associated with the Mistra Biotech programme.

Scrutiny of 400 articles

The group reviewed published research, some 400 scientific articles, to investigate how far GMOs are affecting agriculture. The study covers genetically modified plants, animals and microorganisms alike, and how they affect ecosystem services such as yield, nutrient balance, biodiversity and flows of greenhouse gases.

One key result is that the ecological effects are often indirect. In other words, it is not the genetically modified trait of the plant or animal concerned that affects the cultivation system. Instead, the introduction of a GM crop or organism has entailed new routines for weed control or a different way of working the soil.

‘Where herbicide-tolerant crops have been introduced into farming, spraying to get rid of weeds is easier than before. This means that you don’t have to plough the soil as much, and it affects biodiversity but also how much tractors are used and thus how much carbon dioxide is emitted,’ says Anna-Karin Kolseth.

Persistent knowledge gaps

Kolseth does not exclude the risk of new genetically modified traits directly impacting on ecosystems in the future. Moreover, results from present-day research on, for example, effects on yield or influence on soil-living microorganisms are inconsistent. More research is required, in Kolseth’s view: there is, for example, a major need for more long-term studies.

‘Although any ecological effect from a genetically modified crop is small, it may have repercussions on evolution in the long term.’

Kolseth would also like to see more basic research on the biological mechanisms that affect the cultivation system. But this calls for increased interdisciplinary collaboration among agronomists, ecologists, molecular biologists and biochemists.

‘By learning more about the effects of characteristics on ecosystems and the underlying mechanisms, regardless of whether GMOs are involved, we can develop current cultivation systems towards more sustainable farming,’ she concludes.

Text: Henrik Lundström, Vetenskapsjournalisterna

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