Genetically Modified Food
by Terence Ip
In the present day, the growing issue of food shortages is being exacerbated by the ever increasing population. To combat this, efficient crop growth is a constantly updated field of research. For centuries, farmers have been enhancing desired characteristics and traits in crops through the method of artificial selection. This method can actually be fairly time consuming and is only capable of strengthening existent characteristics in the crop. The newer method being investigated, is that of genetic engineered or modified foods. This method has advantages over artificial selection in the fact that the process of refining characteristics in the crop can be sped up and entirely foreign genes with desired traits can be introduced to the crop genome.
Increasing a plant's tolerance to cold temperatures and rate of growth or decreasing the amount of essential water required by the plant are all possible objectives in genetic modification. All of these methods and more can be used in conjunction or individually to result in higher crop yields. In order to introduce these advantages to the crop, the gene responsible for the trait is isolated and then inserted into the crop genome.
As an example, the cycle of creating Bt corn or Bacillus thuringiensis will be explained. Pests and insects are a major problem in the food production industry with vast amounts of money poured into buying pesticides and the distribution of them over the crop. This is where Bacillus thuringiensis bacterium come in. The bacterium is capable of producing a protein that is lethal to certain types of insects or pests such as the European corn borer. So the Bt gene is taken and then encoded into the corn genome so that, if successful, the plant will be able to produce its own protective pesticide.
To begin the cycle the Bt gene is isolated within its DNA chain by enzymes known as restriction endonucleases which can be used as scissors, in the correct circumstances, to cut out the gene. This gene is then made into an expression cassette by adding the promoter and terminator genes to either end of the Bt gene. This expression cassette is then inserted into the plasmid where it can be copied thousands of times (plasmid is a parasitic circle of DNA found in bacteria). These Bt genes are then absorbed by the host cell where they and become a part of the corn cell genome. The cells that take to the new DNA modification are then grown in a cell culture which in turn is used to create the new crop.
Crop growth can be accelerated and refined by many factors other than just pests, such as producing more nutrients with less water, resistance to drought etc. However, researchers have to be careful before implementing these methods as there can be undesired side effects from the genetic modifications. Going back to the Bt corn example, it was found that the corn produces a pollen which is harmful to the monarch butterfly and several species of caterpillar. So, whilst research in genetically modified food can maximise crop yield the idea can be shrouded in controversy and possible after-effects.
Arshad Chaudry, August 2004, Genetically modified foods, viewed 14th March 2012, < http://www.scq.ubc.ca/genetically-modified-foods/>