Understanding Biotechnology

What is Biotechnology

Overview of Biotechnology

History of Biotechnology

Why do we do biotechnology?

Biotechnology for the environment

Biotechnology for food and agriculture

What is canola?

Canola or rapeseed (Brassica napus) is a bright yellow-flowering member of the Brassicaceae (also known as the mustard) family. It is cultivated for the production of animal feed, vegetable oil for human consumption and biodiesel.

Worldwide, canola was the third leading source of vegetable oil in 2000, after soy and palm oils. Canola is also the world's second leading source of protein meal.

Natural rapeseed oil contains erucic acid, which is mildly toxic to humans in large doses but is used as a food additive in smaller doses. Canola is a specific variety of rapeseed bred to have a low erucic acid content. Canola was developed in Canada. Its name is a combination of 'Canada' and 'oil' (Canadian oil low acid).

Why do we grow canola?

Canola oil has one of the lowest, if not the lowest, level of saturated fat of all the vegetable oils. Saturated fats contribute to health problems such as heart disease. In addition, canola oil has higher levels of the important and beneficial omega-3 fatty acids compared to some other vegetable oils.

The amount of each of these fats produced by an animal or a plant is generally controlled by its genes. It might be possible in the future for us to change these genes in canola plants so that they produce less saturated fats and more unsaturated fats, making canola even healthier to eat.

What’s the problem with weeds?

Weeds can also be noxious to animals that eat the weeds, or the insects that are beneficial to our crops.

To get rid of weeds in a small garden is easy – we can pull them out or dig them in. If the weeds are growing in a path, we can use a herbicide: a chemical designed to kill plants or inhibit their growth. There are selective herbicides that only affect particular types of plants.

Getting rid of weeds in crops is not easy, as they usually grow intermingled with the crop plants. Most farmers have to remove weeds mechanically. This is not always desirable, because mechanical weeding, called tilling, can degrade soils.

A more convenient method, which is less physically damaging to the soil, is to spray weeds with a herbicide before the crop begins to grow. Spraying continues after the crop has grown, to control weeds that grow at the same time. Usually, the spraying is carried out using an aircraft or a boom sprayer pulled by a tractor. Although spraying is carefully regulated, problems can include:

• If the wind conditions are not right, it can be hard to control where the herbicide falls.
• The herbicide can drift onto houses, other valuable plants and into dams, creeks and rivers. This may lead to concerns about the health of people, plants and animals living close to the sprayed areas. High levels of pesticide use have been linked to severe skin and eye irritation, and to breathing difficulties in people living in affected areas.
• It is often difficult to get the right weather conditions for spraying at exactly the right stage in the growth of the weeds and crops.
• The herbicide must kill the weeds, but not harm the crop species.
• A single herbicide may not kill all species of weeds, so a mixture of chemicals may be required.
• Generally, a few individual weeds are not killed by a herbicide because they may be naturally resistant. These individuals may produce offspring that are also naturally resistant. This means that the number of weeds resistant to the herbicide used may increase from year to year.

Alternative approaches to the use of herbicides in the control of weeds are being investigated. One such approach is the idea of biological control; an organism is introduced into the environment that consumes the weed, but does not harm other plant species including the crop plant.

Using herbicides to kill weeds

Environmental considerations

Glyphosate has some advantages over other herbicides. Although glyphosate dissolves well in water, it sticks to soil particles. The soil itself could be washed into river systems, but the glyphosate would end up in the aquatic sediment and not in the water.

Because it binds to soil, glyphosate does not leach into groundwater or poison crops through the roots. Glyphosate is also much less poisonous to animals (including humans) than many other herbicides. Microbes break glyphosate down relatively quickly, so the herbicide does not remain in the soil for long periods of time.

However, glyphosate can kill all the plants it falls on – both crops and weeds.

A number of other herbicides are also available to farmers; for example, atrazine, glufosinate or bromoxynil. Farmers may spray their crops with at least two different herbicides, because some weeds may be tolerant and survive the spraying with the first herbicide. Those weeds are often killed by the second or third spraying with a different herbicide.

A biotechnology solution to weeds

To do this, the genes responsible for herbicide tolerance need to be transferred into the crop plants.

There are four ways to create herbicide-tolerant plants.

1. By natural selection

If a large population of a plant species is sprayed with herbicide, a few plants will survive, flower and produce seed. Some of these seeds will contain the genes that allow the plant to tolerate the herbicide. This herbicide tolerance is passed on through generations of offspring. An increasing number of these plants will survive being sprayed by the herbicide.

If this process of allowing plants that survive exposure to the herbicide to develop and produce seed is carried out enough times, most seeds produced will be tolerant to the herbicide. The herbicide will no longer kill these plants.

For example, canola crops grown in Australia have some natural tolerance to herbicides. This natural tolerance has been enhanced by the process of selectively breeding herbicide-tolerant canola plants.

2. Using naturally occurring genes

TT canola – a conventionally bred strain of canola resistant to the herbicide triazine - is grown across Australia. In Western Australia, it makes up approximately 90 per cent of the total canola production in that state. This form of canola was bred by using genes that were already present in the canola's gene pool.

3. Using mutagenesis

Mutagenesis is the alteration of genes using chemicals or radiation. Mutagenesis can be used to create herbicide-tolerant plants. Then, using traditional cross breeding, crop plants with favourable characteristics and herbicide tolerance can be selected.

An example of a crop made using this technology is Clearfield® canola, marketed by BASF. Varieties of Clearfield® canola have been bred using conventional methods to be tolerant to imidazolinone herbicides, which include the marketed brand On Duty®. These conventionally-bred herbicide tolerant canola varieties are widespread across Australia. Similar herbicide tolerance systems have also been developed for wheat and maize.

4. Using gene technology

Glyphosate is a very effective herbicide. Only five species of plants worldwide are known to have developed resistance to glyphosate through natural selection. Developing herbicide tolerance in a wide variety of crop plants for this herbicide through natural selection is not likely to be easy.

A common soil bacterium gene, which causes a plant to be tolerant to the herbicide glyphosate, has been inserted into a line of canola. The Roundup Ready® canola variety will not be affected when the weeds in the same paddock are killed by spraying with glyphosate.

When using gene technology to modify plants, conventional breeding techniques still have to be used to breed the new trait into the commercial varieties for crops.

Not all herbicide-tolerant GM plants are resistant to glyphosate. The Bayer variety InVigor® canola has been created using gene technology, so that it is resistant to Liberty®, the Bayer glufosinate-ammonium herbicide. Rice is another glufosinate-ammonium resistant crop.

Concerns about herbicide tolerance

The use of herbicide-tolerant crops and their relevant herbicides has the potential to control weeds better, but only if a cautious approach is taken in their management. Care needs to be taken to prevent weedy species developing resistance to the herbicide.

Information on the regulations governing the release of herbicide-resistant crops can be found on the website of the Office of the Gene Technology Regulator (OGTR): www.ogtr.gov.au

In 2003, the OGTR approved the commercial release of the two types of herbicide-resistant canola – Roundup Ready® and InVigor®. In 2008, GM canola will be grown commercially on a small scale in Australia for the first time.

Concerns about GM herbicide tolerance

• the plants will 'escape' into the natural environment and become a problem,
• the plants will interbreed with other plants in the environment and produce 'super-weeds' that are resistant to a number of herbicides
• there will be a transfer of the gene to non-GM and organic crops.

Plants may escape if their pollen or seeds are taken or are blown outside the paddock or farm.

Pollen is carried by the wind, insects or other animals. Farmers have no control over where the pollen from their plants ends up. However, it is possible to change the pollen-making genes in a plant, so that the plant produces no pollen, or pollen that is not able to produce seeds. The latter would not work well for crops where we use the seeds, such as canola.

One technique that is being considered is the insertion of genes into the plants' chloroplasts. Chloroplasts contain the plants' green pigment, and lie outside the nucleus. Because chloroplasts are not within the nucleus, they are not passed on in pollen. As a result, the GM plants cannot exchange their inserted genes with other plants and make weeds that are difficult to control with herbicide.

The most commonly used crop plants are hybrids (crossbred). Hybrids generally produce seed that can germinate, but the resulting plants will not have the same vigour as the parent, and so are unlikely to survive for long.

However, if the plants do 'escape', they will only survive and become a potential problem if they have properties that enable them to compete successfully with plants already in the natural environment. French researchers have claimed that there is a greater risk of GM plants escaping into the wild from GM seeds being left in the fields than GM pollen being blown away from crops.

Is GM canola good or bad?

People who think this GM canola is a good thing say that it:

• is safe to eat
• is better for the natural environment, because glyphosate is less toxic than other herbicides and is not washed into waterways
• helps to minimise tilling and soil degradation
• enables farmers to have a choice on the weed control strategy they use
• saves farmers some of the time and the labour costs of spraying
• improves profits because farmers get better crop yields, since the crop is not competing with weeds
• is better for company shareholders, because company profits are increased (although Monsanto is the company that most people associate with GM food, there are in fact more than 20 other companies currently producing GM seeds, such as Advanta, Novartis, Dow, Pioneer, Bayer and Syngenta)
• is better for the seed merchants, because they can sell higher quality seeds at a higher price.

The people who are worried say that GM canola:

• may produce substances in the plants that are harmful to humans and farm animals
• may cause the plant to produce oil that does not have as much food value as unmodified canola
• may outcross with with other plants including weeds and make them herbicide resistant
• may not be good for farmers because the seeds tend to be more expensive to purchase than the traditionally used seed
• may encourage farmers to use more glyphosate, making weeds more likely to develop resistance.

A number of these points of view appear contradictory. One needs to examine the evidence to decide whether or not each of these views, for or against the use of GM seeds, is valid. Apparently opposing points of view may be valid, depending on the circumstances.