Outside of drought and hail, insects and weeds are the worst threats to agricultural crops, so it’s not surprising that those pests were the first to be attacked by genetic engineers.

Weeds were the first targets. In the 1980s, Monsanto already produced the powerful herbicide Roundup. It works by disrupting the action of an enzyme that is found in almost all plants but not in humans. The problem was how to apply Roundup to the plants you don’t want and keep it off the plants you do – get it on the weeds while keeping it away from the crops. That’s tough to do, so farmers were using Roundup early in the growing season to kill weeds that sprouted before the crops, and then switching to less powerful herbicides after the crops germinated.

Genetic engineers wondered if they could find a gene that would allow crops to survive and even thrive when they are exposed to Roundup. The reasoning was that the pesticide worked on enzymes, and enzymes are proteins that are produced by genes – therefore, there might be a gene that could protect the crop from the pesticide.


Professor Don Lee (right) says that the scientists found their resistant gene in an unusual source that was actually natural. “Monsanto, the company that developed Roundup resistance went looking for Roundup resistance in nature,” he says. “And guess where they found it? They went to bacteria that were in the waste water treatment facility of their one of their Roundup manufacturing plants!”

In the early 80s, workers at a Roundup manufacturing plant in Louisiana noticed that bacteria were breaking down the chemical residue left over. Scientists took 20 different bacteria from the waste facility and found one of that was totally immune to the effect of Roundup or other glyphosate pesticides.

The next task was to put the gene from the bacteria into crop plants.

In 1987, Monsanto started field trials with GMO biotech plants. It took until 1996 to complete the tests, get the regulators to approve of the new hybrids and introduce to the world “Roundup Ready Soybeans.” Farmers could now plant the soybeans, wait for the weeds and the crop to come up and spray once with Roundup. The weeds would die and the crops would grow without the pressure from competing weeds.

In 1997, Monsanto introduced GMO varieties of canola and cotton.

Other companies used similar strategies. For example, the German firm AgrEvo had their own powerful herbicide named “Liberty,” that killed plants by disrupting their ability to use nitrates from the soil. In 1995, they introduced in Canada a genetically modified variety of canola that could resist the action of Liberty herbicide. In 1997, their GM corn variety was introduced in the U.S.

The European corn borer was the next pest to be attacked by GMOs in 1996 with the introduction of “Bt corn hybrids.” The corn borer is the most damaging insect pest of corn throughout the U.S. and Canada with losses exceeding $1 billion a year in the 1990s.

For decades, agricultural scientists have known that a common bacteria found in the soil can produce toxins that are deadly to insects but harmless to humans because they are destroyed within seconds by the acids in the human digestive tract. The bacteria are known as Bacillus thuringiensis and the toxins they produce – not surprisingly – are known as Bt toxins. There are thousands of different kinds of Bt bacteria and they produce different toxins that affect different insects. In fact, organic farmers have used these Bt microorganisms for decades since they produce natural insecticides.

In the early 90s, genetic engineers realized that the genes of Bacillus thuringiensis were what produced the Bt toxin, and they found a way to isolate those specific genes. They transferred those genes into a second bacteria – Agrobacterium – that has the ability to get into the nuclei of plants like corn and transfer genetic material to the corn. Then, they figured out how to find the specific plants that had been altered by including other genes that were resistant to chemicals like antibacterial drugs.

Mycogen and Ciba Seeds (now Novartis Seeds) first introduced Bt corn hybrids in 1996. Farmers found out that the corn borers died after eating only a few bites of the Bt corn plant. Monsanto was not far behind with its own Bt corn, and other companies like Pioneer have either developed their own strains or licensed the technology from other companies.

Bt technology has also been used to attack other insect pests in cotton, potatoes and soybeans.

Since then, there have been a number of new genetic modifications to a wide variety of crops –

  • Sweet potatoes have been enhanced with more protein and other nutrients.
  • Golden rice has been modified by the International Rice Research Institute to provide a low level of Vitamin A. They spliced in genes from the daffodil plant that produce the vitamin, also known as beta carotene.
  • Carrots have been modified to provide at least a little calcium.

Agricultural scientists are now taking genetic modification further by “stacking” two or more genetic traits in a single plant. In one variety, there eight different genetic modifications in a single hybrid of corn.

Written by Bill Ganzel, the Ganzel Group. First published in 2009. A partial bibliography of sources is here.

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