GM plants and the environment

Our ability to create genetically modified plants ("transgenic plants") has generated widespread debate about the potential long-term effects on the environment. The use of genetically modified (GM) crops varies dramatically between countries. For example, the United States planted 35 million hectares of GM crops in 1999, while France planted just 1500 hectares in the same year. These differences reflect political, economic and scientific concerns about the risks involved and the potential benefits. The French group "Interactions plantes et micro-organismes de la rhizosphère" (Plant-microbe interaction at the Rhizosphere), led by Yves Dessaux at the Institute for Plant Sciences, CNRS, has carried out a careful analysis of the direct impact of transgenic plants on the bacterial microflora living around their roots. They studied the consequences of the expression of foreign genes in the roots of GM Lotus plants. Genes from the bacteria Agrobacterium tumefaciens were introduced into the GM plants, enabling them to synthesize opines, a series of molecules which are not usually present within and outside the plant root system. The researchers found that opine synthesis affected the density of bacterial communities degrading these opines in the neighboring soil. They then investigated the long-term effects following elimination of the GM plants. Removing the transgenic plants resulted in reduced densities of bacterial communities degrading opines, but not always to basal levels, whereas replacing the GM plants with wheat cereals eliminated the opine-related effects. Furthermore, they found that the results depended on the introduced transgene, an observation which led them to caution against generalizations about the effects of GM crop and GM crop rotation. Clearly, GM plants can affect bacterial colonization-even when they are no longer present-but in a way which remains limited compared to what happens in a field upon rotation of non-GM crops. This approach presents a framework for evaluating the risk of GM plants and offers insights into the dynamic relationship between plants and their environment.

GM plants and the environment

n° 392 - April 2001

Our ability to create genetically modified plants ("transgenic plants") has generated widespread debate about the potential long-term effects on the environment. The use of genetically modified (GM) crops varies dramatically between countries. For example, the United States planted 35 million hectares of GM crops in 1999, while France planted just 1500 hectares in the same year. These differences reflect political, economic and scientific concerns about the risks involved and the potential benefits. The French group "Interactions plantes et micro-organismes de la rhizosphère" (Plant-microbe interaction at the Rhizosphere), led by Yves Dessaux at the Institute for Plant Sciences, CNRS, has carried out a careful analysis of the direct impact of transgenic plants on the bacterial microflora living around their roots. They studied the consequences of the expression of foreign genes in the roots of GM Lotus plants. Genes from the bacteria Agrobacterium tumefaciens were introduced into the GM plants, enabling them to synthesize opines, a series of molecules which are not usually present within and outside the plant root system. The researchers found that opine synthesis affected the density of bacterial communities degrading these opines in the neighboring soil. They then investigated the long-term effects following elimination of the GM plants. Removing the transgenic plants resulted in reduced densities of bacterial communities degrading opines, but not always to basal levels, whereas replacing the GM plants with wheat cereals eliminated the opine-related effects. Furthermore, they found that the results depended on the introduced transgene, an observation which led them to caution against generalizations about the effects of GM crop and GM crop rotation. Clearly, GM plants can affect bacterial colonization-even when they are no longer present-but in a way which remains limited compared to what happens in a field upon rotation of non-GM crops. This approach presents a framework for evaluating the risk of GM plants and offers insights into the dynamic relationship between plants and their environment.


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