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When growing crop plants or breeding animals for food, farmers select the best animals and crops that suit their needs – this can be the best milking cow, highest-yielding crop or juiciest fruit. These characteristics are largely controlled by the plant’s or animal’s genes.
Sometimes when you cross two plants you can end up with what you want and the bonus of something you don’t. For example, you may get a plant that has juicy fruit but is also susceptible to disease. Sometimes these traits cannot be separated and are said to be linked, meaning that the genes for these two traits are very close together on the chromosome. Extra crossbreeding may be able to separate them, but this is not always possible and takes some time.
Plants and animals with desirable traits can also be bred using modern biotechnology and gene technology. The process can be more selective by finding the genes that control a particular characteristic and the plant or animal can be changed one specific characteristic at a time.
Reproductive technologies such as cloning can be used to produce identical organisms, each with a specific characteristic. This can produce herds of identical animals or fields of identical crop plants.
Although the selected traits may be useful, one drawback of cloning a whole crop is that the crop or herd of identical organisms risk succumbing to the same disease or a parasite. Genetic diversity is nature’s way of ensuring that some members of a species will be immune to a given threat so that the species can survive.
In nature, different species cannot interbreed, so our ancestors selected and bred with characteristics within the species.
One big difference now is that gene technology can be used to transfer genes from one species to another. This can even be between species that have been separated for hundreds of millions of years by evolution (for example transfer of a gene from a bacterium into a plant). A much greater range of traits can, therefore, now be bred into an agriculturally important species. This has led to a concern that gene technology allows scientists to ‘play God’.
Gene technology can be used in agriculture and food production to:
- increase crop or animal resistance to pests while reducing the use of chemicals,
- increase crop or animal tolerance to chemicals that are used to kill harmful pests,
- create disease resistance in crops and animals,
- improve the food yield per plant or animal,
- make plants and animals more suited to special environmental conditions such as drier regions or saline water, and
- improve the nutritional quality of the food produced by the plant or animal.
Gene technology is also being used to deliver benefits in the forestry and fishery industries.
In Australia there is a lot of research into the agriculture and food applications of gene technology. So far, commercial use of the products of this Australian research has been limited to Bt cotton, (also called Ingard® or Bollgard®II cotton), and five varieties of genetically modified (GM) carnation (Florigene Moon series).
The most common GM crops grown overseas are soybeans, corn, cotton, sugar beet, and beet grown for use in processed foods or in animal feed. Ninety-eight percent of GM crops are grown in four countries: Canada, the USA, Argentina, and China. Other countries that have approved GM crops are: South Africa, Australia, Mexico, Bulgaria, Uruguay, Romania, Spain, Indonesia, Germany, India and the Philippines.
Products from these crops may be a part of the food we eat in Australia, if approved by Australia’s food regulator.
Fish genes in tomatoes
Scientists have tried to transfer a gene from the Arctic flounder fish to tomatoes. It was hoped that transgenic tomatoes containing this protein could be used to produce products with better freezing quality, so that they could be frozen and thawed without going mushy.
The experiments were stopped because they failed to work. The antifreeze proteins were present in the tomato, but they did not improve the texture of the tomato fruit following freezing, so there are no tomatoes with fish genes in existence.
Consumer choice in food and agricultural products - work sheet [PDF 57kb | 5 pages]