Fear of a GM Planet III: Crop drift and cherry picking

Fear of a GM Planet III: Crop drift and cherry picking

If the AGM debunked evidence isn’t enough, they can resort to cherry picking. One AGM site takes to task a claim in the early Aughts. It was a sensational claim by a Dr Emile Frison who proclaimed that the banana was on the verge of extinction and the only thing that could save it was GM. Well, as it turned out that wasn’t exactly true and he worked for the multinational agribusiness, Syngenta.

The AGM site GMWatch correctly pointed that out and cited some legitimate research that showed there were other ways to save the banana. But here’s where it gets tricky. They reprinted a letter from banana scientist, yup, you read that right, banana scientist, Dr. David Jones to New Scientist Magazine taking issue with that claim, saying other methods of conventional breeding would work. However, GMWatch neglected to add the last two sentences: “Many banana scientists, including me, believe that genetic engineering should complement rather than replace conventional breeding strategies. (emphasis mine) Let’s not put all our eggs in one basket.”

The intention is to mislead the reader into thinking that Jones is against GM. And I could be wrong here, but I believe Dr. Jones’ statement saying that GE should compliment existing strategies is a common position in the scientific community.

The issue of drift is a big concern of the AGMs and they claim that drift from GM crops will contaminate non-GM crops.

The truth is that drift can occurs even with conventional crops and varies from crop to crop. Farmers take this into consideration when planting and take steps to minimize it. Plant geneticists do the same thing. They factor in, on a case by case basis, that probability and according to the likelihood of that happening.

One of the big pieces of misinformation that gets passed around and repeated is the story of how GM corn pollen on the U.S. Mexican border was contaminating corn crops in Mexico. While the story of contamination is true, scientists are at a loss to figure out how it happened.

Corn pollen is “heavy” and doesn’t drift that far. The fact sheet for Ohio University’s Horticulture and Crop Sciences says that “at a distance of 200 feet from a source of pollen, the concentration of pollen averaged only 1% compared with the pollen samples collected about 3 feet from the pollen source The number of outcrosses is reduced in half at a distance of 12 feet from a pollen source, and at a distance of 40 to 50 feet, the number of outcrosses is reduced by 99%…The number of outcrosses is reduced in half at a distance of 12 feet from a pollen source, and at a distance of 40 to 50 feet, the number of outcrosses is reduced by 99%. Other research has indicated that cross-pollination between corn fields could be limited to 1% or less on a whole field basis by a separation distance of 660 ft., and limited to 0.5% or less on a whole field basis by a separation distance of 984 ft.”

So, how did Mexican corn get contaminated? The region where it took place is the Sierra Norte de Oaxaca region which is almost in Guatemala, at the bottom of Mexico. Given what the data says in the previous paragraph, it seems something else was afoot. It should also be noted that this took place in 2001.

A Guardian article from 2001 reported that GM corn was banned in Mexico in 1998 and the closest field was 60 miles away and that was too far for the pollen to travel, “It was not clear yesterday when the contamination took place, but the scientists speculated that it originated from GM maize bought from the US as food aid for the impoverished region in central Mexico, and had progressed over time via multiple pollinations.”

So, while there was cross-pollination, the facts lean toward the idea that it was imported corn and not cross-border “drift” as the AGMs claim.

Next we come to the idea that GM plants have not been thoroughly tested and all kinds of scary mutations can happen including causing pregnant women to give birth to babies with cabbage heads. Okay, maybe not cabbage headed babies.

Anastasia Bodnar is doctoral candidate at Iowa State University in genetics with a minor in sustainable agriculture. She addressed this issue in some detail elsewhere and gave me permission to post it here. So, here are some of the facts surrounding this issue:

Plants that have been genetically engineered undergo many levels of screening and breeding to remove unwanted mutations.

Genetically engineered crops are tested by event. An event is a single instance of a gene being integrated into the genome of a single embryo or other plant part (depending on the species being genetically engineered). Sometimes the gene will integrate in the middle of an important gene and effectively cause a mutation (those would be removed from the breeding program). Other times the gene will integrate in a place where it isn’t interfering with other genes, which is what we want.

In the process of creating a genetically engineered crop a lot of events are created, and they are tested to see where the gene integrated and if there are any strange characteristics that might indicate an unintended mutation. Any plant that isn’t what the breeders/genetic engineers want is destroyed. The events that pass then go through a breeding process called backcrossing, which essentially replaces all the genetic material from the transformed plant line with genetic material from an untransformed plant line, except for the region around the gene that was inserted. This ensures that any mutations caused by the transformation process are not left in the final line.

Mutations happen all the time. There are natural mutations due to DNA replication errors and due to mutagens like UV light from the sun. There are all sorts of strange chromosomal rearrangements when two related species are crossed. And so on. There are also intentional mutations caused when a plant breeder exposes seeds to a chemical or radioactive mutagen to try (on purpose) to induce mutations that might produce new and valuable traits. What happens if there are harmful mutations? If a plant breeder notices something weird in one of the plants, it’s removed from the breeding population and either destroyed or kept for further study if it is interesting.


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