Genetic engineering is just an extension of natural breeding
Genetic engineering is different from natural breeding and poses special risks
GM proponents claim that genetic engineering is just an extension of natural plant breeding. They say that GM crops are no different from naturally bred crops, apart from the inserted foreign GM gene (transgene) and its protein product. But this is misleading. GM is completely different from natural breeding and poses different risks.
Natural breeding can only take place between closely related forms of life (e.g. cats with cats, not cats with dogs; wheat with wheat, not wheat with tomatoes or fish). In this way, the genes that carry information for all parts of the organism are passed down the generations in an orderly way.
In contrast, GM is a laboratory-based technique that is completely different from natural breeding. The main stages of the genetic modification process are as follows:
- In a process known as tissue culture or cell culture, tissue from the plant that is to be genetically modified is placed in culture.
- Millions of the tissue cultured plant cells are subjected to the GM gene insertion process. This results in the GM gene(s) being inserted into the DNA of a few of the plant cells in tissue culture. The inserted DNA is intended to re-programme the cells’ genetic blueprint, conferring completely new properties on the cell. This process is carried out either by using a device known as a gene gun, which shoots the GM gene into the plant cells, or by linking the GM gene to a special piece of DNA present in the soil bacterium, Agrobacterium tumefaciens. When the A. tumefaciens infects a plant, the GM gene is carried into the cells and can insert into the plant cell’s DNA.
- At this point in the process, the genetic engineers have a tissue culture consisting of hundreds of thousands to millions of plant cells. Some have picked up the GM gene(s), while others have not. The next step is to treat the culture with chemicals to eliminate all except those cells that have successfully incorporated the GM gene into their own DNA.
- Finally, the few cells that survive the chemical treatment are treated with plant hormones. The hormones stimulate these genetically modified plant cells to proliferate and differentiate into small GM plants that can be transferred to soil and grown on.
- Once the GM plants are growing, the genetic engineer examines them and eliminates any that do not seem to be growing well. He/she then does tests on the remaining plants to identify one or more that express the GM genes at high levels. These are selected as candidates for commercialisation.
- The resulting population of GM plants all carry and express the GM genes of interest. But they have not been assessed for health and environmental safety or nutritional value. This part of the process will be discussed later in this document.
- The fact that the GM transformation process is artificial does not automatically make it undesirable or dangerous. It is the consequences of the procedure that give cause for concern.