Most, if not all, of the food crops we consume today has undergone some form of modification. About 10,000 years before the inception of biotechnology, man domesticated crops and animals he gathered from the environment that surrounded him. During the domestication process, better plant materials and healthy animals were selected for propagation and breeding. Consequently, the selection for desirable traits by farmers for over thousands of years improved plants and animals for agricultural purposes.
The traditional form of breeding, known as selective breeding, involves the propagation of plants with desirable characteristics or by combining qualities from two closely related plants or animals.
These traits may be resistance to a particular pest or disease, or tolerance to harsh climatic conditions. This method of breeding has produced successful new varieties of crops over the years, but it has also failed to produce results on several occasions. As a result of the unpredictable nature of this method at the genetic level, desirable traits such as disease resistance could also be bundled with undesirable traits such as low yield or poor quality. Besides, traditional breeding could take several years to yield results; the process is labour intensive, and is not always economically feasible. These drawbacks probably fueled the quest to develop new methods of modifying plants.
In 1940, plant breeders found that they could increase the rate at which mutations occur in plants. They realized they could use radiation and chemicals to change a plant’s DNA, the double helical molecule that houses the genes of all living organisms. Altering the DNA of a plant may give rise to a new variety with desirable characteristics. Induced mutation breeding, as this process is called, has been used to develop about 2,500 crop varieties; however, only a handful of varieties are produced using this technique today; this is largely due to the advancements in genetics and molecular biology.
It is now well established that the basic structure of DNA is identical in all living cells, and the variations in organisms are determined by the sequence of the DNA base pairs (two nucleotides on opposite complimentary DNA strands that are connected via hydrogen bonds). Our understanding of genetics has deepened to the point where it is possible to transfer one or more specific genes from almost any organism including plants, animals, bacteria or viruses into the genome of another organism. This is referred to as recombinant DNA technology, and it was first used to produce synthetic insulin on a commercial scale.
Currently, the technology is widely used to develop new plant varieties and animal breeds. Thus, in agriculture biotechnology, alterations are made directly to the plant’s or animal’s DNA sequence. The process begins with the identification of the gene that determines a desirable trait (in the donor organism); this particular gene is then selected, extracted and later transferred directly into the genome of the host organism. Organisms that have genes from other organisms are known as transgenic or genetically modified organisms (GMOs).
GMOs possess novel features that enable them to either survive harsh climatic conditions, be more resistant to pests and diseases, synthesize chemicals that non-GMOs could not, or produce high yield and good quality. Some GMOs are engineered to be resistant to herbicides and other agro-chemicals. Examples of genetically modified (GM) crops include pest resistant cotton, maize, and canola (mainly Bt or Bacillus thuringiensis); glyphosate resistant potato, papaya and squash. Also, a number of GM corps are being developed with traits of bio-fortification, phytoremediation, and production of pharmaceuticals; for instance, golden rice is a GM rice that has high levels of carotenoid for production of vitamin A which could reduce the occurrence of blindness, and bananas are being engineered to supply vaccines.
Commercial production of GMOs begun in the early 1990s, and by 2004, 81 million hectares of land distributed among 17 countries were cultivated to GM maize, soybean, cotton, and canola. Presently, GM crops are commercially grown on about 150 million hectares in 22 developed and developing countries. The United States and Canada are the largest developed-country producers of transgenic crops, while Argentina, Brazil, China, and India make up the largest developing-country producers.
Follow up for (Pt2): Prospects and Challenges