ANNUAL SYMPOSIUM

Australia's science future 3-4 May 2000
Full listing of papers

Dr Carolyn Schultz received a PhD from New York University in 1995 for studies on nitrogen metabolism in plants, using molecular biology and genetic tools to gain a better understanding of how plants use nitrogen. Since then she has worked at the University of Melbourne School of Botany for the CRC for Industrial Plant Biopolymers and now for the CRC for Bioproducts. Her work has focused on using biotechnology to develop products for the food and pharmaceutical industries, using plant cells in suspension culture.

Symposium themes - Genetic engineering of plants and animals
Genetic engineering: Food for the world with less environmental impact
by Carolyn Schultz
c.schultz@botany.unimelb.edu.au

Abstract
Genetic engineering of plants has been around for more than 100 years. New 'recombinant' DNA technologies allow scientists to target the changes they make. Dr Schultz will explain this technology and show how engineered plants are similar to the plants we eat everyday. Most plants contain around 22,000 genes. These genes provide the blueprint for how each plant is made. By adding one extra gene (from sunflowers) to rice plants, scientists have been able to develop plants that produce 'golden' rice grains that make the precursor to vitamin A (beta-carotene). Golden rice is expected to prevent eye disease in millions of children in developing countries. Genetic engineering of plants will lead to the merging of food and medicine – for example, edible vaccines. It will also benefit the environment by reducing pesticide use, cleaning contaminated sites and allowing plants to grow in droughts or regions high in salt.

Genetic modification has been going on for hundreds, even thousands, of years. Recombinant DNA is a new technology for doing this.

Today’s tomatoes and corn are the result of extensive plant breeding or genetic modification programs. Tomatoes come in a wide range of varieties from which breeders can select the best characters. The traditional corn plant is nothing like what we eat now. Only five or six genes contribute to the plant’s important qualities.

We are eating foreign (non-human) DNA and proteins all the time; they are broken down in the gut.

A gene is a DNA recipe for a single protein. The DNA code is like 1700 books of 1000 pages each. One gene is only one or a few pages.

Using the old breeding techniques for, say, the tomato, the breeder would take one variety that tastes nice and cross it with one that resists disease to get the best characters. That is like taking two stacks of DNA books, shuffling them and sifting through the results. It is unpredictable and a lot of work.

The new techniques are more predictable and offer better control. The breeder inserts one gene into one DNA book. The gene could come from a wider variety of sources. There is still a lot of testing to make sure it works and see that it is safe.

The benefits of genetic modification are:

• in developing nations, farmers can grow more productive plants to feed growing populations, as well as more nutritious food;
• in Australia, where we often choose unhealthy foods, genetically modified foods can reduce fat intake, modify allergens and improve health;
• in the environment, genetic modification offers tools to fight weeds and pests, and in doing so will reduce our impact on the environment. It will also allow us to grow plants in soils of poor quality.

Rice does not contain the beta-carotene from which our bodies make vitamin A. In countries where rice is a major part of the diet, many children go blind. The production of vitamin A is controlled by enzymes. We can insert genes to control these reactions. Golden rice, created by a group of Swiss scientists, contains beta-carotene. It will be important for nutrition for developing nations.

Vaccination can control disease. The active agents can be inserted into a food plant, such as bananas. Then people will get protection by eating the vaccine.

Pests such as rust (a fungus) cause crop losses. We can insert a rust-resistance gene to give the crop plant a defence. This reduces the need for sprays and maintains productivity.

Salinity is increasing in our soils. This has been caused by tree removal and irrigation. It could take more than 100 years to rehabilitate the land. Some plants, such as saltbush, can soak up salt. We can insert a salt pump gene into crop plants or trees so that they can grow in poor soil. Other modified plants could remove heavy metals from contaminated sites. So genetically modified plants could play an important environmental role.

There will be a merging of food and medicine, for example in edible vaccines. We will have better health by taking the gluten out of wheat, for example. There will be less damage to the environment, by reducing pesticide use and helping plants to grow in soils affected by drought, salt and heavy metals.

If we take a positive view of the technology the question is: how do we make it happen? We need to conduct risk-benefit analyses, case by case. We need good regulations that are transparent and involving everyone. And we need an informed public. The new Gene Technology Information Service is providing information (not opinions) on all aspects of biotechnology (phone 1 800 631 276).

Session discussion

Who is going to benefit from this technology? How can the benefits be passed on to everyone in the world?

Carolyn Schultz. Whoever is paying for the research controls it. We have to rely on foundations that do work to benefit developing nations.

Peter Rathjen. We have to make sure there is adequate competition so one company cannot tie up the technology. Patent control is the key thing. We need resources for breakthroughs and to stay at the table.

Are edible vaccines broken down in the gut?

Carolyn Schultz. DNA is broken down into building blocks but this is not always so with proteins. The vaccines are fused with disabled cholera toxin to make them stable, so that they are taken up through the gut lining.

Are we going to get hydroponic meat?

Peter Rathjen. There is an important technical barrier to that. We can multiply cells but we can’t make them organise into their final form. Scientists in the USA are making organ and tissue scaffolds. Meat may be possible in the next few decades.

What are the risk factors of genetic modification?

Carolyn Schultz. The risk factors that have been reported – such as increased herbicide resistance – would happen with existing methods. Other risks are exaggerated such as the suggestion that modified corn would kill monarch butterflies. The basis of this report was due to poorly designed experiments. We need case by case field testing and assessment of risks.

Frank Gubler. Modified cotton pollen cannot be transferred to native cotton.

What is the potential and the risk of the transfer of stem cells or differentiated cells descended from stem cells?

Peter Rathjen. Embryonic stem cells would not be transplanted as they do cause cancers. Their immortal potential is lost after differentiation. We can control and eliminate carcinogenic effects. We are learning how to do it.

Is there more known about reprogramming cells?

Peter Rathjen. One possibility is to inject a nucleus into an embryo and then isolate the stem cells. With humans this is ethically fraught. But it may be possible to directly reprogram from an adult cell to a stem cell without going through the embryo.

Dolly was not identical to her mother, she was prematurely aged. When will we truly clone?

Peter Rathjen. I doubt we will want to truly clone. Mitochondrial DNA won’t be important for the immune system. Genetic modifications can be made in the nucleus. I’m not sure of the advantages of doing it to mitochondria.

This work depends on public perceptions. We are not doing well at informing the public. In terms of regulation, the new gene technology Bill gives the public less access than they have now. How do we turn public opinion against the bad but not the good?

Carolyn Schultz. I don’t know that you can do a lot more. You have to get the benefits to the consumers, not the companies. It is not going to happen in a hurry.

Frank Gubler. People don’t object to genetically modified medicines.

Peter Rathjen. The Swiss, in a referendum, almost banned genetic engineering. There is little known about genes. Biology is not studied extensively in schools – education programs have to be improved.

What causes side effects?

Peter Rathjen. There is not sufficient hard data. This has to be solved before the technology is applied.

Frank Gubler. The testing of plants, especially foods, needs to be rigorous.

The public has a strong input into legislation. We need a new breed of scientists to educate the public.

Why are people worried about the ethical consequences of gene technology?

Carolyn Schultz. That does not apply so much to plants. The main problem is a poor understanding of what a gene is. It is hard to see big ethical problems, people are more concerned about environmental issues.

Peter Rathjen. The destruction of human embryos raises ethical problems. Ethical concerns are often based on ignorance; that will pass. People may apply technology in all sorts of ways. Mad people will do mad things. We can’t design legislation against stupid uses.

Scientists explaining is not adequate. We must improve science teaching.

Stem cells are found throughout the human brain. We could gain neurons as we age. In Parkinson’s disease we may be able to reproduce, migrate and connect cells to remove the condition. There are great prospects for stem cell work.

Will the beta-carotene in golden rice by inactivated by heat (cooking)?

Carolyn Schultz. We boil carrots and still get the benefits.

Some dangers are associated with biotechnology. One concern is the vectors (viruses and bacteria) used in cloning and the introduction of genes into cells. Another is that inserting genes into positions we cannot predict may modify the expression of some genes, producing effects that we cannot predict.

Carolyn Schultz. There is a very small risk of transfer of antibiotic resistance. Resistance genes are already very abundant in the bacteria or our gut and the soil. New markers are being developed.

Peter Rathjen. We no longer use viral and bacterial vectors in animals. We don’t leave behind things we don’t want.

Frank Gubler. In plants we have moved away from antibiotic-resistant genes. We just use the genes we want.

How many genes does it take to modify cattle hooves so that they do less damage to our environment?

Peter Rathjen. I can’t guess.

There is a need for early education about science, using programs such as the Academy’s Primary Investigations . Primary science is very important.

There are limitations to how much you can educate the general public. Some people just regard certain things as unnatural, for example they believe that natural chemicals are different from laboratory chemicals.

Carolyn Schultz. There are some who won’t buy a synthetic food colouring or flavouring, even if they have the same chemical structure as the natural ones. We are unlikely to be able to convince these people that GMOs are beneficial.