Plant Biotechnology & Gene Technology: They're not the same. This Ground Cover special liftout explains what they are. Biotechnology The Biology of the future.
GroundCover™ Issue: 30
Benefiting the grains industry
Biotechnology refers to a wide range of techniques common in agriculture, medicine and industrial production which use biological processes to create new products. Modern plant breeding uses these biological 'tools' on a regular basis.
In crop production this has become possible because fundamental research in the past 20 years has provided new understanding of how plants grow and develop, how they synthesise component parts such as starches, oils and proteins found in seeds, and how they respond to the environment.
Fundamental research has often led to the identification of important genes that control key processes of plant growth and function. Plant breeders have used this genetic knowledge to develop desirable traits and new varieties.
While direct insertion of new genes into plants, to create a so-called genetically modified organism, has captured most media attention it is currently a small part of a whole range of biotechnology tools.
As you will see below, under conventionally accepted methods, it is not unusual to introduce new genetic material into crop species by crossing species barriers.
As a rule, the tools of biotechnology have greatly speeded up the process of developing new crop plants.
Biotechnology: today's toolkit
Breeding for complex traits such as grain quality or disease resistance is a major challenge because the trait is often not easy to see, requiring analysis of the grain or infection. A new grain quality trait, for example, may require laboratory analysis of grain from thousands of plants during the process of introducing the trait into elite varieties.
If we find the gene responsible for a trait it gives us a perfect marker for that trait so that the plant breeder can easily determine which plants in his breeding program contain this gene. A small leaf sample is used to look for the DNA fingerprint of the gene of interest.
New characters for selection
An excellent example is water-use efficiency in wheat. Although an important trait for Australian wheat production, it is very difficult to measure and therefore difficult to breed for.
Biotechnology, developed from Australian research into the process of photosynthesis, has provided a rapid method for the breeder to select wheat plants that are more efficient in their use of water. With this method, thousands of plants have been screened and new genetic material identified with major increases in water-use efficiency. The trait has now been introduced into regional breeding programs where yield increases up to 20 per cent have been recorded.
Under conventional methods, the plant breeder introduces new genetic variation by crossing different genetic lines, but then must repeatedly self-cross the new lines to select the desired characteristics and to produce a true breeding variety that is genetically homozygous.
The doubled haploid technique accelerates the process of producing true breeding lines and is used in wheat, barley, rice, rye, maize, canola and pepper. This is accomplished by regenerating plants from haploid pollen cells which contain only one set of chromosomes and genes, rather than the two sets found in cells of the non-reproductive part of the plant. The chromosome number is doubled so that the plant will have a duplicate set of identical genes and will breed true.
Cell culture techniques are commonly used to overcome the normal barriers to sexual crosses between species and to improve the transfer of the alien genes to cereal germplasm.
There are many examples where valuable genes have been transferred between species, especially those conferring resistance to plant diseases. Resistance to barley yellow dwarf virus was transferred to wheat from a wild grass, Thinopyrum intermedium.
Plant biologists have learned how to regenerate whole plants from single cells or small parts of plants. This opens up the possibility of producing thousands of identical copies (clones) of a plant with desirable characteristics. Although not currently applicable to broadacre crops, clonal propagation plays an important role in horticulture and forestry where each plant has a relatively high value.
Tools to speed up conventional plant breeding
Diagnostic technologies for disease management
Knowing what soil organisms are in the paddock and in what quantity, before the crop is planted, is an important part of disease management. But this is a difficult and slow process using standard identification techniques, especially when it is hard to tell the 'bad guys' from the 'good'.
Biotechnology has provided a cheap, rapid and accurate solution to the problem. Each organism has its own DNA fingerprint that can be used to distinguish it from other species. A diagnostic system for soil pathogens, fungal, bacterial and nematode, has been developed in which DNA is isolated from all organisms in a soil sample and the fingerprints of the 'bad guys' tell us who is there and in what amount.
Product quality assurance
DNA fingerprinting technology can also be used to identify and distinguish crop varieties. Premiums paid for growing a special variety may involve a test to confirm the identity of grain being delivered. Other rapidly performed tests have been developed to measure specific quality properties of the grain or to detect rain damage.
Many research projects supported by growers and the Federal Government through the GRDC use these technologies.