Farmers have always selected plants for their superior properties, and crossed species to produce required properties. The difference between natural breeding and genetic modification today is that conventional breeding involves crossing genotypes expressing many thousands of genes, and selecting the offspring with the best features, which has the drawback of creating a plant with a random assortment of genes. This method of breeding for desired qualities is also limited by the fact that only closely related plant species can be interbred. Genetic modification allows the isolation and transfer of specific genes, and allows them to be transferred across species. Since all plants comprise a universal DNA, DNA from different organisms can be cut and spliced.
Plants are being modified for a number of reasons. Crops such as sugarcane are being developed that resist herbicides (Gallo-Meagher and Irvine, 1996); researchers from Cornell University have developed a strain of rice which can survive drought and saline soil conditions (Cornell U, 2003); strains of corn, soybeans, cotton and canola have been developed which are resistant to the weed-killer Roundup (Anderson, 2003); a strain of soybean has been developed in which the gene for a structural protein that causes soybean allergies in some people has been developed (Miller, 2002); and the development of ôgolden riceö in which two plant genes and one bacterial gene have been added so that beta carotene is synthesized in the edible portion of the plant rather than just in its leaves, is supplying much-needed vitamin A to many of the worldÆs undernourished peoples (Kohl, 2001).
Genetic modification of plants has many other applications in food production, such as: delayed softening and improved ripening of tomatoes to extend shelf life; producing virus-resistant squash and papaya to improve nutritional value; fungus-resistant bananas to resist viral infections;
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