Are chemicals or drugs used?
Expert response from Community Manager
Moderator for GMOAnswers.com
Thursday, 09/05/2019 19:57
There are many breeding techniques utilized in modern agriculture including selective breeding, mutagenesis and genetic engineering, among others. Beginning in the 1920s, plant breeders started seeking more diversity than they were able to achieve through selective breeding to create new traits. Through mutagenesis they began to make changes in plant deoxyribonucleic acid (DNA) by exposing seeds to chemicals or gamma irradiation and then selecting the plants that displayed the traits they wanted. More than 3,200 varieties of commonly consumed plant products have been developed using mutagenesis, including varieties of red grapefruit, bananas, peanuts, peppermint and rice.
With genetic engineering, chemicals are used when researchers are developing a new, transgenic version of a plant in the growing media. Steve Savage, Consultant, Savage & Associates, explains that when researchers are developing a new, transgenic version of a plant they start by adding the intended gene(s) and regulatory elements at a single cell level. This is usually done using strains of the soil inhabiting bacterium Agrobacterium tumifaciens which is “nature’s genetic engineer” that is good at inserting a circular bit of DNA that then integrates into the DNA of the plant cell. The wild version of that bacterium turns the cell into a growth on that plant that houses and feeds the bacterium, but for plant genetic engineering those negative genes are removed and the intended new gene is what gets inserted. In order to identify the plant cells that actually got and incorporated the new genes, a “selection marker” is added as part of the package. This consists of a gene for resistance to something like an antibiotic or resistance to a herbicide like glufosinate. The antibiotics used here are relatively old like hygromycin or kanamycin. Those chemicals are put in the growing media for the plant cells so that only successfully modified cells can grow. Each one of these cell lines is considered an “event” and the next step is to decide which events have the new genes inserted someplace in the plants DNA where is does not interfere with any other important genes.
Once a good “event” has been identified, that cell line is grown out into a whole plant that can now be entered into the normal, “conventional breeding” process so that it will be in all the varieties that are best suited to different regions etc. From that point on there is no further involvement with the selection marker chemicals in further breeding or when the crop is grown by the farmers. In modern breeding, the new trait can be efficiently followed using genetic sequencing information as the gene is moved into the elite, conventional breeding stock of the crop species.
We hope this answers your question, if you have any other questions about GMOs or biotechnology, please ask!