BIOLOGY Volume 3 - A Guide to General Biology - 2004

25. APPLIED GENETICS

25.3. Genetic Engineering of Eukaryotes

Eukaryotic organisms can be modified using Introduction/32.html">Genetic Engineering techniques just like Bacteria. Organisms that have been genetically altered through Genetic engineering Methods are commonly referred to as transgenic.

The production of transgenic organisms offers an alternative to traditional PLANT AND ANIMAL breeding methods, representing a promising new direction in agriculture. Improving plant varieties or animal breeds through conventional methods is a lengthy process that largely relies on probabilistic events occurring during meiotic Crossing-over and the random segregation of Chromosomes during sexual reproduction. For instance, developing a new cereal variety takes 7 to 12 years. Genetic engineering makes it possible to introduce new genes into an Organism, "designing" plants and animals with desired traits. Much like bacteria in fermenters, Transgenic Plants and animals can become "living factories" for producing valuable products, beyond just food. A major goal of agriculture is to increase food production in developing countries, and it is hoped that these new technologies will help millions of people overcome hunger. However, The Use of transgenic plants and animals also raises A number of ethical and environmental concerns (Fig. 25.12).

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Fig. 25.12. Newspaper headlines in The Times, The Sun, and the Evening Standard addressing the issues of genetic engineering.

Below are some of the key objectives in agricultural plant and animal breeding that can be alternatively achieved by creating transgenic organisms:

1) increasing productivity;

2) improving product quality (e.g., vegetable oil, fat, and protein content);

3) enhancing resistance to pests and diseases — resistance genes can be transferred from one species to another;

4) increasing resistance to environmental stresses, such as drought, cold, heat, overcrowding (for animals), and soil acidity, salinity, or waterlogging (for plants). Genes controlling stress responses can be isolated and transferred from one organism to another;

5) increasing growth rate, i.e., the time from birth (or planting) to maturity; the geographical range of certain agricultural crops could potentially be expanded by shortening their growth period;

6) increasing herbicide resistance (Section 25.4.4).

The advantages of Genetic Engineering in agricultural improvement over Traditional Methods are as follows:

1) a Gene responsible for a specific trait can be identified and cloned;

2) all desirable characteristics of an existing variety or breed are preserved, while the targeted gene is simply added to them;

3) generating transgenic organisms takes significantly less time than traditional selective breeding.