Modern crop breeding makes use of biotechnology to produce new varieties with improved yield and product quality. These new varieties also must be compatible with or contribute to sustainable farming practices. This presentation will focus on one aspect of biotechnology, gene technology, the introduction of new or altered genes into plants in the laboratory.

Genes are made of DNA, a large molecule found in every cell of every living organism. Every gene is made of the same four units, the only difference between genes being the order of the four units of the genetic code. DNA is a part of food and the average person consumes 2 X 10¹⁶ genes per day. As a food, these genes are the same regardless of whether they come from a plant, animal or microbe. When a gene is activated, or turned on, it directs the synthesis of a specific protein according to its code, the order of the four units. The protein products of genes have different functions and may have different food properties. A few may even be poisonous or cause allergic-type reactions.

The primary contribution of gene technology to date has been in scientific investigations in which a great deal of new knowledge has been gained about how plants grow and develop. In the course of these studies, genes with potential for application in breeding have been isolated and their beneficial properties have been demonstrated in the lab and glasshouse. Although a number of potentially important genes have been identified, very few have been deployed into commercialised cultivars.

Once a new, beneficial gene has been identified, it is introduced into plant cells by one of two methods. The new gene can be transferred by the soil bacterium Agrobacterium as part of a natural process in which a small amount of bacterial DNA is introduced into the plant. In the biolistics method, tiny gold particles are coated with the new gene and then shot into the cell using pressurised gas. The result of both methods is that the plant cell now has one new gene in addition to the approximately 50,000 it already had. Whole plants are then regenerated from single, genetically transformed cells.

I will give four examples of different applications of gene technology to illustrate the range of current applications. In the first, gene technology is used to transfer a beneficial gene from a related species into a crop plant. The rust diseases are serious problems for wheat growers in Australia. These diseases are primarily controlled by using resistance genes.

A source of resistance genes is rye. Until now, transfer of resistance genes involves an interspecific cross between wheat and rye, followed by several generations of backcrosses of the hybrid with wheat to eliminate as much of the rye genetic material as possible while retaining the resistance genes. In practice, the method is imprecise and many rye genes are incorporated into the new wheat variety, some with undesirable characteristics. A major research effort at CSIRO Plant Industry over a 15-year period resulted a world first isolation of resistance genes for rust diseases. These genes can now be transferred from other species to wheat and barley with precision.

In the second example, gene technology is used to introduce a gene from an unrelated species or to introduce a gene constructed in the laboratory. Insect damage is the major problem facing cotton growers and large amounts of insecticides must be applied at many times during the growing season to control pests. These insecticides are an imprecise solution, lacking specificity and killing both pests and beneficial insects, in addition to a host of other detrimental environmental effects.

Organic farmers use a natural insecticide, called Dipel, to combat caterpillars. Dipel contains a protein produced in the spores of the bacterium, Bacillus thuringiensis, that is toxic to caterpillars. Scientists have isolated the bacterial gene coding for the toxic protein, modified it in the laboratory to work effectively in plant cells and then transferred to cotton. Extensive glasshouse and field trials demonstrated the efficacy of the Bt gene in killing cotton budworm and related caterpillars.

The first Bt gene in Australian cotton is owned by Monsanto and is marketed with the name IngardÒ . Although IngardÒ does not provide complete insect control, it has reduced insecticide applications by half. In addition, extensive monitoring of the cotton crop by CSIRO has shown a second major benefit of IngardÒ technology to be the return of beneficial insects with the reduction in pesticide usage, especially early in the growing season.

Many of these beneficial insects are predators of cotton pests and can play an important role in controlling the growth of pest populations. In this example, gene technology results in the production of a protein inside the cells of the cotton leaf that would not otherwise be found there. But this insecticidal protein is commonly applied to the outside of leaves, especially in organic farming operations.

In the third example, gene technology is used to turn off the function of a plant gene, resulting in no new protein, rather the absence of one normally present. An artificial gene is made in the laboratory by reversing the code of the gene we wish to turn off. This new gene produces an antisense messenger RNA but no protein. The effect of the antisense RNA is to block the translation of the normal messenger RNA into its protein product.

Plant breeding has exploited rare mutations to remove unwanted genes. The breeding of canola relied on the identification of a mutation that prevented the synthesis of unwanted oils in the seed of the rape plant. The use of chemical mutagens can speed up the process, but the process is still imprecise and other deleterious mutations are likely to arise at the same time.

Antisense and related technologies are being used in many laboratories worldwide to modify the oil composition of oilseed crops, especially canola. Oil synthesis in the seed is a multistep process, each step catalysed by a protein enzyme coded for by a specific gene. Removing the activity of one of these enzymes, delta-12 desaturase, prevents the conversion of oleic to linoleic acid.

The resulting high oleic oil is a high value oil because of its stability at high temperatures and is therefore a superior cooking oil. Although the current Australian canola seed crop is in high demand in Europe because no GM canola is grown here, experts predict that demand will shift in a few years to canolas with high value oils.

The final example illustrates how gene technology can control virus diseases of plants. Potato leaf roll virus is a serious problem, limiting yield and damaging the product. Because the virus is spread by aphids, it is controlled by insecticide sprays to kill the aphid. Knowing when and how much to spray is always difficult. CSIRO scientists have synthesised a gene containing a small part of the virus and have shown that this gene is effective in preventing virus disease.

The technology works so well transgenic potato plants are said to be immune because they exhibit no symptoms of disease and virus replication is prevented, thereby blocking the spread of the disease. The synthetic gene produces a small RNA but does not produce any viral protein. Just as in the previous example, the technology is used to turn off function.

Field trials at multiple sites have proven its performance under normal farming conditions. The potato plants are indistinguishable from non-transgenic potatoes, except when they are challenged with virus and the non-transgenic plants show disease symptoms.

How does gene technology move from the laboratory to the paddock? From the initial discovery of a new gene, there is a great deal of experimentation and testing in the lab and the glasshouse, followed by repeated small and larger scale testing in the field.

All steps are closely regulated and the resulting data examined at each step. Once the performance of a new gene has been demonstrated in the field, it then enters a breeding program to introduce it into elite varieties. Product testing and final regulatory approvals are necessary before it is released as a commercial crop variety to be sold to the farmer.

The experience with cotton in Australia is that varieties are available with and without the new gene, in this case, IngardÒ , giving the farmer a choice. Gene technology must prove its worth; otherwise no grower will be interested.

Although the first GM varieties in commercial use contain single introduced genes, most future varieties will have several introduced genes. This so-called "gene stacking" will provide traits benefiting the farmer and other traits benefiting the consumer. Examples are cotton with several insect toxin genes and genes for herbicide tolerance.

The use of at least two different insect toxin genes dramatically reduces the rate at which the caterpillars develop resistance and further reduces the need for supplemental insecticide sprays. This benefits the farmer by reducing input costs and the consumer by reducing pesticide residues in cotton, cottonseed oil and crops and livestock grown nearby.

Introduction of a herbicide tolerance gene into a crop means that more effective herbicides can be used against weeds, which often means lower levels of application. Canola varieties will be released soon with a number of new traits including herbicide tolerance, resistance to fungal diseases and high value seed oils. Some of the new canola varieties will also be hybrids showing significant yield increases.

Many technologies are required to produce a new variety with an introduced gene and most of these technologies are covered by patents. For example, the methods of introducing a new gene into a plant cell and then regenerating a plant from that cell are protected by a number of patents. Therefore, any company wishing to commercialise a new GM variety must obtain commercial licenses for all technologies used to make that variety.

However, licenses for these technologies are not all readily available. Ownership of a key technology that everyone needs to use could potentially block competitors from entering the GM seed business. One solution is to gain access to key technologies through R and D partnerships with the owners of that technology. Successful partnerships are the ones where both parties have attractive technologies to trade.