AgBiotech Infosource: Issue 23 September, 1996
Biotechnology and Cereal Crops
Meeting the never-ending demand for improved grain varietiesA Never-ending Quest
Grains such as wheat and barley have been mainstays of Canada's economy for centuries. Wheat, an annual grass which originated in the Middle East, was first brought to Canada from Europe almost four hundred years ago by the Champlain colonists. In the 1640s, Canada achieved self-sufficiency in wheat production and by 1654 the grain was being exported.
Wheat growing accompanied the movement of European settlers westward through the country: it was first grown successfully in the prairie region in 1824. Today, Canada produces 30 million tonnes of wheat annually, 70 per cent of which is exported, generating billions of dollars of income.
Technical innovations have always influenced the choice of the wheat and other grain varieties grown on Canadian farms. In the 19th century, improved milling techniques shifted demand from softer varieties to the hard red spring wheats that grew best on the Canadian prairies. Improving the milling and baking quality of wheat has been a top priority of plant breeders ever since.
Plant breeding (the selection and development of superior genetic types of plants) has also been used to develop grain varieties that can withstand epidemics of disease or insect pests and produce higher yields.
Plant breeders for Agriculture and Agri-Food Canada have
produced about 90 per cent of the wheat cultivars
(cultivated varieties) grown in Canada in the
past 100 years. The demand for new varieties continues to
grow, based on:
- changing conditions in the natural environment, such as the emergence of new crop diseases or pests;
- the need for higher productivity to satisfy the food needs for an expanding world population;
- new consumer markets, such as the growing Asian demand for flour suited to noodle making; or
- the specialized requirements of new food technologies, such as frozen dough production.
Increasingly, plant breeders are turning to biotechnology to develop better grains. Biotechnologies such as genetic engineering offer plant breeders a powerful means to supplement and complement the traditional methods that they have used so successfully in the past.
Developing Biotechnology for Cereals
Traditional methods of plant breeding employ managed, sexual crosses between the same plant species or its wild relatives to incorporate desirable traits into a crop. Since 1984, genetic engineering has been introduced as an additional method to alter the inherited traits of plants.
Genetic engineering is a process by which genes (the parts of a cell that provide blueprints for inherited traits, such as colour) are "cut" from the cells of one organism and "pasted" and integrated into the cells of another organism. Once the cells are transformed, they are grown into new plants capable of "expressing" the desired characteristic. Genetic engineering allows plant breeders to obtain genetic traits from sexually incompatible organisms, such as entirely different plant species, bacteria or even animals.
Most of the transgenic (genetically engineered) plants produced to date have been non-grains, especially oilseeds such as canola. Oilseeds respond more readily to biotechnologies that use bacteria to "ferry" genes through the cell wall of the target plant. Grains do not respond well to this technique (although it has been used successfully to transform rice). However, in the late 1980s, scientists at Cornell University invented a biolistic method (a kind of gene "gun" used to "shoot" genes through cell walls) that is more effective in genetically modifying cereal grains. It is the only method that has worked to genetically engineer wheat.
Making a Transgenic Grain
Using the biolistic method, the Cereal Biotechnology Group at the National Research Council's Plant Biotechnology Institute (PBI) in Saskatoon has succeeded in producing fertile, trangenic wheat. Transgenic wheat was first field-tested in 1994 in collaborative trials conducted by PBI, the Crop Development Centre at the University of Saskatchewan and AgrEvo Canada.
The transformation procedure used at PBI combines the biolistic gene transfer technique with a technology called the Enhanced Regeneration System (ERS), first developed by PBI scientists. How does it work?
- ERS is PBI's proprietary technology used to produce a large number of wheat plants (up to 15) from a scutellum (a part of an immature plant embryo in a developing wheat grain).
- Scutella are first isolated from the seed of the plant targeted for genetic transformation. Using the biolistic method, genes carrying a desirable trait are "shot" into isolated scutella of donor wheat plants.
- The scutella are then grown into plants using tissue culture techniques (methods of producing plants from their tissues rather than from their seeds).
- If a new plant produced from a part of a scutellum has been "hit" by the foreign genes, and if the genes are incorporated into the genetic makeup of the targeted cells, a transgenic wheat plant is produced in four to five months.
The ERS system has been used to produce transgenic wheat, but can also be used to transform other grains.
Transgenic Wheat
In addition to the biotechnology developed at PBI, two other laboratories in the U.S. and one in Germany have reported the genetic transformation of wheat.
Genetic technologes have also been used to transform a number of other grains, including wheat, corn, rice, oats and barley.
The biotechnologies developed at PBI have already resulted in transgenic wheat that is resistant to the herbicides glyphosate and glufosinate ammonium, which normally damage wheat plants. Herbicide-resistant wheat allows farmers to use a wider variety of chemicals to control weeds, to rotate the chemicals used and to reduce chemical inputs by increasing the flexibility of chemical application.
Other transgenic grains that have been successfully developed to the commericial stage include corn resistant to the European corn borer and to the herbicide Roundup. Scientists have also succeeded in developing transgenic rice resistant to leaf blight and to an insect pest.
These successful demonstrations of genetic modifications in cereal crops opens the door to a wider application of the technology.
Goals of Biotech Research
Now that successful cereal biotechnologies have been demonstrated, researchers are examining a wide range of possibilities for improving the productivity and quality of cereal crops.
- Given increasing world population, improved cereal yields will continue to be a top priority for plant breeders. Insect pests and weeds are a major cause of crop loss: in developing countries, 100 million tonnes of cereals and legumes, enough to feed 300 million people, are lost each year to pests alone. Developing crops with an inbred resistance to herbicides and to insect pests will continue to be an important research goal.
- Biotechnology could be used to increase the ability of cereals to withstand drought, frost or soil salinity. Although such capabilities are extremely complex (because they involve a larger number of genes and environmental influences than does resistance to a specific chemical or pest), they will remain a long-term research goal.
- Genetic engineering can be used to improve the nutrutional quality of cereals. For example, researchers are working on transgenic barley varieties with improved malting qualities.
- A priority in wheat research is the development of varieties with a wider range of processing qualities. While biotechnology can be used to further improve the baking qualities of wheat flour, a priority for research involves the starch content of wheat. Markets for Canadian wheat are shifting from Europe, where people favor leavened wheat products, to Asia and the Middle East, where wheat is mainly consumed as noodles or flat breads. With biotechnology, the starch quality of wheat may be altered to produce flours that are better suited to these rapidly expanding markets. Altering starch quality can also enhance the use of wheat for industrial purposes such as adhesives or fuel ethanol.
Clearly, biotechnology is opening the door to a much broader range of cereal crop options. Transgenic grains will provide opportunities to create new markets for Canadian farmers and add substantial value to Canada's agricultural products.
Special thanks to Dr. Ravindra Chibbar of the National Research Council's Plant Biotechnology Institute for his support in producing this Infosource.
If you would like to receive future issues in this series of agbiotechnology information bulletins for schools, please contact:
Ag-West Biotech Inc.
101 - 111 Research
Drive
Saskatoon, SK, Canada S7N 3R2
Phone:
306-975-1939
Fax: 306-975-1966
E-mail: Ag-West Biotech Inc.
WWW:
http://www.agwest.sk.ca
Published by:
Westcross House Publications
608 Duchess
Street,
Saskatoon, SK, Canada S7K 0R1
Phone:
306-934-1772
Fax: 306-664-6615
Funding assistance provided by Saskatchewan Agriculture and Food