1. The relevance of oilseed rape cultivation

Enzymes are macromolecules, mostly of protein nature, that occur in all living organisms. Acting as natural catalysts, they enable the biochemical reactions necessary for life to take place by increasing the reaction rates. Enzymatic reactions require neither high temperatures nor high pressure conditions, and are therefore less energy-intensive than processes dependent on chemical catalysts. Enzymes have a high specificity. In general, an enzyme catalyzes only one reaction type and operates on only one type of substrate.
Many different enzymes exist in organisms, working in the digestive system, in the metabolic processes and helping the synthesis of certain compounds. Some pesticides and herbicides work by interfering with enzyme systems, or by destroying them altogether.

2. Development of transgenic varieties - transferred properties

The development of transgenic oilseed rape is aiming at a lot of different targets.
Work under way includes:

• Development of herbicide tolerant rapeseed varieties

• Development of male sterile rapeseed varieties used in the production of hybrid seed

• Qualitative and quantitative modifications of the sperm composition

  1. Modification of the fatty acid composition in rapeseed oil

  2. Production of rapeseed oil containing provitamin A

  3. Production of "bioplastics"

• Development of rapeseed varieties with improved resistance towards pests and diseases

• Improvement of the feeding quality of the canola meal

• Drug production in oilseed rape plants

The development of new rapeseed varietes by means of genetic engineering is in progress. More than 1.000 patents for industrial applications of oilseed rape already exist. Below you will find some illustrative examples of the progress made in modern breeding of oilseed rape.

3. Herbicide tolerance of oilseed rape

Up to April 1999, a total of 300 applications for the release of genetically modified oilseed rape varieties had been placed in the EU. In addition to herbicide-tolerance properties (226 applications), male sterility (83), modified plant metabolism (49) and fungus resistance (21) were the subjects of the applications.
Both glufosinate and glyphosate tolerance have been transferred to various genetically optimized oilseed rape varieties, making it possible to employ easily biodegradable herbicides in their cultivation. The mechanism of action of the tolerance towards glyphosate and glufosinate is described in detail in sections 5.1.4/5.
In Canada, the total acreage of transgenic canola (summer oilseed rape) had reached 2.4 million hectares in 1998, equivalent to 50% of the Canadian Canola area. For the season 1999 there is a further significant increase to 3.24 million hectares (67% of total crop) estimated.

4. Male sterility

Many of our modern-day crops are so-called "hybrids". These originate from parent plants that exhibit significant genetic differences. The aim of such hybrid-cultivation measures is to avoid the familiar negative effects of "in-breeding" (the cross-breeding of closely related organisms). Hybrids produce higher yields and are less susceptible to disease and environmental stress than non-hybrid varieties.
One difficulty that is encountered in the cultivation of hybrids is the fact that many plants bear both male and female reproductive organs on the same plant and thus exhibit a tendency towards self-fertilization (autogamy). In the production of seeds, therefore, efforts are made to use purely female - or more precisely "male-sterile" - plants for cultivation purposes. The pollen is transferred to the female organs manually. In crops with separate male and female plants - as is the case with maize - the male flowers are removed by hand.
Such hybrid-cultivation procedures are highly labour- intensive. An alternative method is presented by hybridization systems in which male fertility or sterility is genetically controlled. Male-sterile plants have been developed both by conventional cultivation procedures as well as by genetic modification. The manual removal of flowers or portions thereof and the manual fertilization of the female flowers by the breeder is therefore no longer necessary.
The genetic modification approach involves the introduction of genes that are active only in the male reproductive organs and that prevent the emergence of the male flowers (or parts thereof). This results in purely female ("male-sterile") plants that can then be used for cultivation purposes and for the production of hybrid seeds.
In the production of hybrid seeds, the male-sterile plants of one parent are planted alongside unmodified plants of the other. The seeds developing in the male-sterile plants therefore can have developed only by the crossing of the two intended parents. An essential feature here is that the hybrid plants that grow from the hybrid seeds go on to form pollen themselves to the extent that the seed of the hybrid plants indeed constitutes the crop to be harvested (e.g. oilseed rape). If on the other hand only vegetable plant organs of the hybrids are harvested (leaves, stems, roots, etc.), the restoration of the pollen fertility is not absolutely necessary (e.g. sugar beet, animal-feed grasses).
Hybridization systems created by genetic modification are used in connection with plants for which there are no simpler methods for the creation of hybrid seeds available. The property of male sterility permits the attainment of high-yield, resistant hybrids.

5. Modification of the fatty acid composition

High-laurate oil: Calgene developed canola plants with nearly 40 % laurate content. Laurate is an interesting ingredient because of its industrial applications in the production of detergents such as shampoos, but it can also be used in food production (i.e. chocolate).
Laurical, the high-laurate canola has been grown commercially in the U.S. since 1994. Making canola produce high amounts of laurate was relatively easy. The genetic modification was based on the introduction of a gene from California bay (Umbellularia californica), with the result that the chain prolongation in the synthesis of fatty acids is terminated after the 12th carbon atom. In this way fatty acids containing 12 instead of 18 carbon atoms are available. The productivity of the canola is not effected by this modification.

Another target of research is the development of high-myristate canola. Myristate can be used in industrial applications similar to laurate.

High-stearic canola: Using oils with high contents of stearic acid in the production of margarine or shortening can make the technical hydrogenation of rapeseed oil unnecessary. These naturally high saturated oils do not contain any trans fatty acids normally produced in the hydrogenation process that contribute to high levels of cholesterol. Thus heart diseases can be prevented.

High-eruca oil: Eruca acid is in great demand as a raw material. In the existing varieties of eruca-oilseed rape its content does not exceed 66 % of the total fatty acid content. The desired enhancement of the eruca acid content can only be achieved with genetic engineering techniques enabling the transfer of genes for suitable enzymes that catalyze processes in the fatty acid synthesis. The corresponding rapeseed varietes will be available on the market soon.

Oilseed rape with short-chain fatty acids: German scientists at the Max-Planck Institute for Breeding Research are conducting research aimed at the development of oilseed rape providing oil with high contents of short-chain fatty acids. The main component of oils made from the existing rapeseed varieties is oleic acid with a fatty acid chain of 18 carbon atoms. For industrial applications fatty acids with chains of 8 to 14 carbon atoms are needed. In the seeds of the Cuphea lanceolata you find 80 % of capric acid, a desired short-chain fatty acid containing 10 carbon atoms. First successes have been made transferring genes that regulate the fatty acid synthesis in Cuphea lanceolata to rapeseed plants.

6. Rapeseed oil with an enriched content of provitamin A

Up to the year 2002 a rapeseed variety with an increased content of betacarotenes in the corresponding oil is expected to be available. This can be used for the prevention or treatment of vitamin A deficiency or the resulting night blindness. In some developing countries vitamin A deficiency is a widespread problem.

7. Plastics made from plants: biopolymers

Biodegradable plastics made from renewable resources are a valuable contribution to waste management. These materials can easily be degraded treating them with certain enzymes produced by microorganisms. As a result the amounts of waste can be decreased. Within the group of bioplastics the focus of interest is lying on the polyhydroxy fatty acids (PHA).
Bioplastics can be produced in transgenic plants e.g. transgenic oilseed rape. Companies like Zeneca Seeds in Great Britain and Monsanto in the U.S. are already conducting research aiming at the development of PHA producing rapeseed.

Modifications of qualitative and quantitative composition of rapeseed sperms:

8. Development of rapeseed varieties with improved resistances against pests and diseases

Fungal resistance: To combat "black leg" and "white mould", two fungal diseases relevant in the cultivation of oilseed rape, scientists of several companies and research institutes (i.e. Zeneca-Seeds) introduced new genes into oilseed rape. These are genes for chitinases and glucanases, enzymes that can degrade the cell wall of the fungi.
Insect resistance: The companies Mycogen and Pioneer Hi-Bred collaborated in the development of rapeseed varieties that are protected against some plant pests by the help of the bacterial Bt-gene.

9. Improvement of the meal quality (feedstuff)

In a collaboration with the University of Delaware the company DuPont has developed new rapeseed varieties with a content of the amino acid Lysin that is twice as high as in conventional canola plants. That considerably increases the nutritional value of this variety. Therefore the addition of certain amino acids to the animal feedstuff that is usually essential for an optimal nutrition is not necessary any longer.

10. Drug production in oilseed rape

The company Sem-Bio-Sys Genetics is aiming at the production of therapeutic substances, like interleukin, an immune-system booster and cancer fighter, from genetically engineered rapeseed plants. The company is also working on the production of Hirudin in oilseed rape. This anti-coagulant is important in treating people who suffer health problems from blood clots (e.g. heart attacks). Producing this substance in canola plants with an inserted gene for Hirudin, could reduce production costs to one-tenth of the price at which it is currently available.

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