Potential ecological risks of transgenic plants : the particular case of plants expressing viral genes

Abstract EN

Many laboratories, including ours, have introduced viral sequences into the genome of host plants as a means of creating artificial virus resistance genes.

These genes are of particular interest in the numerous cases where natural resistance genes are not available.

It can be argued these new viral genes will have a positive impact on the environment, particularly if their use allows reduction in use of pesticides for control of the biological vectors of plant viruses (insects, fungi, nematodes...).

However, there is concern that plants expressing viral genes could have a potential for negative environmental impact as well.

These concerns are based on two classes of modifications of plant/virus interactions.

One class of interactions is based on the ability of viral proteins synthesized by the plant to complement certain functions of the infecting virus.

For instance, in plants synthesizing a virus coat protein, the infecting virus can be encapsidated in particles composed, at least in part, of he protein synthesized by the plant.

which can lead to changes in vector transmission.

Complementation by viral proteins can thus lead to changes in virus phenotype.

There is also evidence that plants expressing viral sequences can also be a source of modifications in the genotypes of infecting viruses.

This would be the case if there is recombination between the viral sequences expressed by the plant and the infecting virus.

Though potential mechanisms for changes in plant / virus interactions in transgenic plants have been identified, we know very little about how this might be translated into potential changes in the epidemiology of virus diseases.

In some cases, for instance with coal protein genes, there may be ways of eliminating certain factors of risk.

Further studies of potential mechanisms should allow us to devise other means of risk reduction or elimination.