A GE urban myth that has grown to become a 'fact'

By TONY CONNER*

Rather than taking the opportunity to present balanced arguments on the sustainable future of our primary industries and the relative merits of genetic modification versus conventional technology, the Sustainability Council has resorted to reiterating the rhetoric of other anti-GM organisations.

This is well-illustrated by Sam Neill's Dialogue article. He presents a series of half-truths and innuendo to develop an argument of GM's unacceptable risk to the environment and human health. Of particular concern was his reference to the Crop and Food Institute's research of toad genes in potatoes at Lincoln.

This example has been used repeatedly by anti-GM groups to generate public fear. The transfer of a gene from toads to potatoes is nothing more than an urban myth that has assumed the status of a scientific fact. It is time to put the record straight.

This project was initiated more than 10 years ago as a novel approach to the development of disease-resistant crops. Many diseases are caused by microbes, such as fungi and bacteria, and the aim was to develop plants that would resist such diseases.

At the time, small protein molecules active against bacteria and fungi were being discovered in insects and reptiles. The institute set out to investigate whether we could design and build plant genes to protect plants against disease infection.

When this project was initiated, one of the best-known anti-microbial proteins was magainin, which was identified in the African clawed toad. An experimental system was required for testing the institute's idea. Potato was the obvious choice because the institute had the most experience in the genetic modification of this crop and it suffers from soft-rot, an important bacterial disease.

Potatoes are easy to test for soft-rot resistance and it was found that magainin was highly active against the soft-rot bacteria. Researchers chose not to transfer the gene for magainin from toads to potato because scientific knowledge suggested that a toad gene would not work in plants. Since the magainin protein is small, it would be more efficient on time and resources to synthesise an artificial magainin gene.

When designing and constructing the synthetic DNA sequence with the genetic information to make magainin in potatoes, researchers used DNA sequence information from other potato genes to ensure the designed gene was potato-like. No toads were ever touched and no genetic material from any animal was transferred to plants.

Furthermore, when the DNA sequence of the institute's synthetic magainin gene is compared to the millions of DNA sequences known from all organisms, it has greater similarity to other plant genes than to the DNA sequence of the magainin gene from toads.

Ten years after initiating this project, it was rewarding to finally produce potato plants that made the magainin protein and were also resistant to soft-rot bacteria. The institute contributed to a scientific development to control plant disease.

The magainin-producing potatoes may have no future, but what has been learned can be applied to other diseases and crops. Despite what anti-GM groups proclaim, researchers never intended these potatoes to be released and grown by the potato industry. This was only used as an experimental system to test a novel scientific concept.

In the future it is possible the synthetic magainin gene could be used with a molecular switch that only permits the magainin protein to be present in the non-edible part of a crop. This could control root diseases in crops where the fruit is eaten.

As expected, science has moved dramatically since this project began. Small proteins with similar properties to magainin have been discovered in other organisms, including humans and plants. They are likely to be discovered in potato or related species in the future. We will then be in an excellent position to quickly adopt a new technology for controlling plant diseases in potato.

In presenting his case against GM, Neill confuses two clear and distinct aspects of the debate: that of ethics versus safety. While animal genes in plants carries a "yuk" factor in the minds of many, it does not mean it is unsafe for the environment or to human health. New Zealand consumers are protected by one of the world's most rigorous regulatory systems governing the safety assessment of GM organisms.

We need to debate the ethical issues surrounding the development and use of GM technology. Many ethicists have pointed out that it may be more unethical not to use a GM technology than to use it, especially in a situation where it can save lives.

We need to debate the relevance of the capitalistic concept of gene ownership in a natural world where genes are common property to many species.

We need to debate where the boundary lies between gene transfers that are acceptable and unacceptable while recognising that in most cases the transfer of genes across more distant natural barriers, such as animals to plants, will involve synthetic genes similar to the situation described above for toad genes in potatoes.

We also must understand that chromosome fragments have been transferred across species barriers over the past four or five decades in conventional crop breeding, especially in wheat.

One of the widest possible gene transfers is between humans and bacteria. We must not forget that for more than 20 years diabetics have been highly dependent on GM insulin produced in bacteria following the transfer of a human gene.

* Tony Conner is a scientist with Crop and Food Research and a professorial fellow at Lincoln University.

Herald feature: Genetic Engineering