Transgenic Plants

Breeding is still an effective mechanism for improvement and is frequently used to increase such traits as yield and disease resistance, as well as characteristic important to food processors (eg. sucrose level in potatoes) and nutritionists (eg. levels of ?-carotene in carrots). However, the great disadvantage that breeders face is the lack of control over the gene mixing that occurs during normal sexual reproduction. When a nucleus from a pollen grain fertilizers a nucleus in an ovule all of the chromosomes of the pollen nucleus are mixed with all of the chromosomes of the egg cell in the ovule. In many cases, undesirable traits are passed to the egg cell along with the desirable traits. In the mid-1970s, plant scientists were quick to see the potential of recombinant DNA technology to revolutionize plant breeding.

Instead of being dependent on characteristics found in other cultivars, or closely related species, plant breeders would transfer genes from virtually any other organism. Furthermore, the wholesale mix of genomes that occurs during conventional (traditional) breeding, does not occur with recombinant DNA technology. Only the desired gene and one or two other genes, depending on the methodology used, are transferred to the recipient plant. This means it is less likely that valuable traits will be lost during the gene transfer. In the early 1980s, the first studies of transgenic plants were published, and in early 1990s, several companies took initial steps towards commercialization of transgenic plants.