The Oxford Science Lecture Series

DR SARAH GURR

Reader in the Department of Plant Sciences, University of Oxford

"GM Plants: A Golden Harvest?"

Martin Wood Lecture Theatre, Oxford, 31st October 2002

Dr Sarah Gurr, Reader in the Department of Plant Sciences, University of Oxford, gave the 23rd Oxford Science Lecture. She gave an overview of traditional biotechnology and then spoke in detail about modern biotechnology, popularly known as Genetic Engineering. She made a strong case for the development and use of GM plants in certain situations.

Dr Gurr comes from a family of medical doctors but has had a lifetime interest in plants. She claims to have learnt her ABC from the Thompson & Morgan catalogue! In due course, she became a 'plant doctor' and now heads a research group looking in particular at plant pathenogenic fungi.

Dr Gurr began by giving an account of traditional biotechnology, where plants and animals are bred to have certain characteristics, often over many generations. For example, wheat has been a staple crop in Europe and the middle east for millennia. There are now around 25,000 different cultivars of wheat, ranging from durum wheat, used to make pasta, which has been deliberately bred to have a low gluten content, to varieties with a high gluten content suitable for baking bread. Similarly, animals have been genetically selected for different characteristics for many thousands of years.

In traditional biotechnology, species can be crossed only with close relatives. Breeding is fairly indiscriminate and results come slowly. Only a few species of plant and animal have been successfully developed in this way.

Modern biotechnology, or genetic engineering, by contrast is able to move genes between unrelated species. It is in some sense more predictable and certainly faster than traditional methods. However, public opinion is in general not in favour of its use.

An example of where genetic engineering could make a potentially positive impact on the world is that of engineering potatoes to resist the common problems of blight and golden eelworm (a parasitic nematode). These are capable of completely destroying whole crops of potatoes. Even with extensive use of pesticides (such as Aldicarb, currently declared safe in the UK but banned in some other countries), 22% of the worldwide crop of potatoes is lost to disease. Predictions are that if potatoes continue to be grown as intensively as now but under organic conditions there will be 100% loss of crop. Traditional agricultural methods such as using disease-resistant species and crop rotation are not sufficiently effective - cysts of golden eelworm can survive for up to 40 years in the soil for example.

Dr Gurr's research team investigated the possibility of using genetic modification to add a gene extracted from the golden eelworm nematodes into potatoes which would cause the nematodes to be unable to feed on them. This gene has no effect on humans, and so could provide a way of reducing the use of pesticides. However, there is currently a moratorium on such work.

Another example is that of Golden Rice and pro-vitamin A. The world population is predicted to reach 7 billion by 2013, and half of the population has rice as a staple. Currently, milling rice (which must be done to prevent the rice going mouldy in humid conditions) leaves the grains lacking vitamin A. In South East Asia, 70% of children under 5 suffer from vitamin A deficiency. Scientists have introduced 3 genes into a rice cultivar, two from the daffodil and one from a bacterium, to produce golden rice which has a high vitamin A content in the grain. This was a considerable feat of genetic engineering. Cultivars will be ready by 2003, and it is estimated that the lives of 2 million children could be saved by an increase in their vitamin A intake. But the huge public outcry against GM foods means that it is possible that golden rice will not be approved for use.

Dr Gurr clearly feels very strongly that sensational journalism and changeable government policies are inhibiting the development of potentially life-saving technologies. The current vogue for organically produced food is not sustainable - there is not sufficient agricultural land in use to feed the world organically. Most of us are not comfortable with the widespread use of pesticides (for example, iceberg lettuces are sprayed up to 9 times before they reach supermarket shelves), so perhaps the only other option is to consider GM foods. When they can prevent health problems, such as in the golden rice case, can we ethically make the decision not to allow their use? Multinational companies such as Monsanto have given GM crops a bad name, but this does not necessarily mean that all research into GM foods has a hidden (and darker) agenda.

Dr Gurr's final thought was that armed with the facts, rather than scaremongering stories, we should all be able to make our own informed decisions about the use of genetically engineered crops. It is clear that she strongly believes that these technologies have a great potential for good, and that they may be the least bad option in the quest to feed the world.

Catherine Hobbs