Mar 6, 2008

Research Results

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Ten years of safety research

Virus-resistant sugar beet - no big deal in environmental terms

Does genetically modified sugar beet with resistance to rhizomania viruses behave differently in the environment to conventional sugar beet? Several safety research projects have looked at different aspects of this issue. After almost 10 years of ecological accompanying research, there are no clear indications that the transgenic beets under investigation play any special role in the environment.

In the meantime, interest in genetically modified sugar beet with resistance to rhizomania viruses has waned. Plans to introduce it on the market have long since been shelved because conventionally bred varieties with strong resistance to rhizomania are now available. However, some of the earlier research projects have provided information about possible environmental effects, which may be relevant for all GM sugar beet, regardless of the introduced trait.

Wild beets: Gene transfer from cultivated beets is possible.

Research projects: summary of results

Topic: Can genes from GM sugar beet outcross to related species (vertical gene transfer)?

Result: Gene transfer between cultivated and wild beet must be expected. In particular, it may occur when cultivated beets are allowed to flower (mainly for seed production) in places where wild beets also grow. There are no essential differences between GM and conventional beets in this respect.

The possible consequences of this type of gene transfer depend on the particular trait. Since rhizomania viruses have not yet been found in wild beet populations, the wild beet does not gain any advantage through the virus-resistance gene. If herbicide resistance is transferred to wild beets, it would be advantageous only if the complementary herbicide was in continual use.

Natural populations of wild beet are found only at a few sites in Europe.

Bolters: Sugar beets do not usually flower because they are biennials: The beet body forms in the first year and is harvested before flowering. If premature flowering occurs (bolting), annual weed beets may appear. It is good farming practice to remove all bolters before they flower.

Topic: Environmental behaviour of transgenic virus-resistant sugar beet

Results:

  • Competitive strength compared with other plants: when infected with the virus, conventional beets are weaker. When there is no viral infection, the transgenic beets fare worse than their conventional counterparts.
  • Overwintering: sugar beet can survive in the field only in mild winters. No differences were found between the overwintering ability of transgenic and conventional beets.
  • Seed vitality (seed weight, seed dormancy in the soil): No differences between transgenic and conventional plants
  • Bolting due to premature flowering. Transgenic beets are less likely to produce bolters.

Topic: Transfer of transgenes from GM sugar beet to micro-organisms (horizontal gene transfer)

Result: It was not possible to detect gene transfer under natural conditions in the soil. Under ideal laboratory conditions it was for the first time possible to demonstrate horizontal gene transfer from transgenic plant DNA to naturally competent bacteria. Despite this finding, the probability of horizontal gene transfer from transgenic plant DNA to bacteria in the soil appears small.

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