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A Plant Breeder Explains How GE Techniques Differ from Non-GMO Breeding

Carol Miller Posted by Carol Miller|November 8, 2017

Back-lit-tomato-slice

With public concern about genetically modified organisms (GMOs), growers often find themselves trying to explain breeding techniques and how their crops are non-GMO. Sometimes, however, growers stumble when explaining how GMO breeding differs from modern breeding.

Bejo Seeds' Senior Tomato Breeder Doug Heath

Bejo Seeds’ Senior Tomato Breeder Doug Heath

So American Vegetable Grower® turned to Bejo Seeds Senior Tomato Breeder Doug Heath, asking him to explain how the two methods of breeding differ.

“GMOs are a hot topic and very misunderstood by many,” Heath says. “It is not odd to fear what is not known, and I wish that there had been much more consumer education regarding GMO crops years ago.”

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Although genetic engineering allows for significant breakthroughs, today’s breeders are still making strides, Heath says.

“Many modern non-GMO breeding techniques have really helped to speed breeding. Use of molecular markers is one of the main techniques. We breeders are now able to know quickly from a very small piece of leaf tissue what is the status with numerous genes, some for resistances and others for quality traits,” he says.

Part of the reason growers find it difficult explaining modern non-GMO breeding is terms like “genetic markers” and “DNA extraction” sounds a lot like GMO breeding.

“These techniques also use automated DNA extraction and analytical equipment, but the major difference is GMO plants are created using techniques that allow for insertion of a gene from one plant to another,” Heath says. “Usually, it is not possible with classical breeding to cross one species to another if reproductive incompatibility exists.”

Heath provides an example of what he means.

“A tomato was created with the Bs2 gene from pepper for bacterial leaf spot resistance. You could not cross a pepper with a tomato by classical breeding, so this tomato was a GMO,” he says. “It was not produced and used because it is felt that the market is not ready for this.”

But if breeders can find useful genes within a species that can be introduced successfully by crossing then there is no need for a GMO transformation.

“Introgression refers to the piece of DNA brought in by classical breeding from one tomato into another and very often in reference to a disease resistance gene,” Heath says. “In this example, the fragment of DNA from the wild accession with the resistance gene is the introgression fragment which often contains more than just the resistance gene. A good examples of such introgression fragments that are large include the initial fragment for nematode resistance [Mi gene] from the peruvianum wild species.”

Looking ahead, Heath is excited about new DNA manipulation techniques, including CRISPR Cas-9, which uses no outside DNA.

“It is hoped we will be able to accomplish even greater goals while keeping the crops completely safe and healthy for consumption,” he says.

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Carol Miller is Editor of American Vegetable Grower. See all author stories here.

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Avatar for Barry Rogers Barry Rogers says:
November 9, 2017 at 8:08 am

This is an example of a good GMO. I am sure there are many. The issue is when we breed a plant food for the sole purpose of selling more chemicals. Companies who do this show a lack of compassion for the end customer and cast doubt on the science who’s intention was , is, for the betterment of Mankind.

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Avatar for Scott Friesen Scott Friesen says:
November 9, 2017 at 10:22 am

More chemicals are not being sold, you actually use less chemicals with GMO’s as the chemical is more efficient and brings down the farms cost of production, as we purchase all input costs at retail pricing and sell everything at wholesale price, we do not share the same privilege as all other industries that have a set mark up price on what they are selling, North Americans spend the least amount of on money on food then any other industrialized nation, perhaps if consumers where willing to pay considerably more for there food agriculture would make the change.

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Avatar for Matt Matt says:
December 14, 2017 at 11:42 am

Hi Scott,

Your statement is actually wrong and is proved so by the USDA. MORE chemicals are used today than were in the past. The difference is the shift in the types and sources of chemicals used. In the past more insecticides were being SPRAYED since crops had not been genetically engineering to produce insecticidal toxins. NOW many row crops have been genetically engineered to produce insecticidal toxins. The difference with plant produced toxins is that they exist in all cells of the plant, even the ones you consume. They also persist longer in the environment as they can not begin degradation until the plant tissue they are found in also degrades. Sprayed chemicals of the same class (BT Toxins) begin degradation very soon after they are sprayed. This is why crops like sweet corn and field corn that rely on BT sprayed must have those insecticides reapplied several times.

The use of herbicides (which is also a part of the pesticide family) has grown exponentially since the introduction of GMO crops. This also coincides with a switch from more traditional weed control methods (Cultivating) to no-till production.

In the last few years more chemicals and specifically more new types have been applied than in any time in history. Many of these new herbicides have significant environmental and agronomic risks. Dicamba tolerant soybeans are one example. Dicamba is actually an old herbicide. It has a high agronomic risk as it easily volatizes (turns into vapor and “moves” miles) and can damage traditional crops (not just soybeans) and gardens for miles depending on the wind and temperature.

The increased use of RoundUp over the last few decades has given rise to many resistant weeds. This leads to the increased use of older, more toxic forms of herbicides or to using large amounts of other herbicides such as Liberty.

So the idea that total chemical use has fallen is wrong. It has increased. The amounts of specific types of SPRAYED chemicals may have gone down, but that only shows a very small picture. Some of the chemicals we use now are more concentrated and in a more pure form. This may mean we have reduced the amount we spray by weight, but the overall environmental burden has gone up. Meaning the amount of active ingredient that has been applied has actually gone up.

It is nice marketing spin to say “We have reduced our application of insecticide by a million gallons.” Most of that insecticide mix is water. What is not mentioned is the amount of active ingredient that is entering the environment from both sprayed and plant produced sources. Which, as you may have guessed by now, has gone up.

In conclusion, it is always best to be distrustful of companies who are not fully transparent with their technology. Farmers and society should be able to make decisions on what technology to use from a fully informed position. They should not rely solely on marketing material and take a companies word for it, especially when profit is the main motivator.

What I DO NOT want to see is wholesale use of CRISPR technology. Humans do not yet fully understand how biological systems work. We know enough to manipulate DNA and effect change, but what we can’t yet do is fully predict how changes to DNA will affect the entire organism. An example is with DNA insertion.

During sexual reproduction most organisms have built-in control within their DNA that only allows certain genes to be inserted in specific locations. This is a plants way of controlling gene expression. When we artificially insert genes, no matter the technology used to accomplish it, we don’t know for certain what the effect will be when it is inserted in different locations of a DNA strand. In one location it may have minimal effect of the expression of other genes, in another it may cause surrounding genes over or under express themselves resulting in a plant that may cause allergies for some people, be more susceptible to disease, etc.

The future of breeding really is marker assisted selection using traditional crossing with production of inbred lines. The DNA technology is not being used to modify, but rather to verify that desirable traits are present. Since this can be done as soon as their is enough genetic material to test (maybe a few leaves), then we can keep only those plants that have naturally received the traits we want and dispose of those that did not. This allows breeders to greatly accelerate hybrid production since the plant doesn’t have to be mature to see if it received the traits we were looking to introduce. What used to take a decade or more can now be done in a few years. Further, breeders can now have access to parent lines with verified traits.

What does this all mean? It means, that if farmers need a crop with a specific disease package, we now have ways to guide natural sexual reproduction to achieve that in a reasonable amount of time. The ONLY limiting factor in this “toolbox” is being able to find genes that impart a resistance to a disease that does not naturally exist with this crops sexually compatible partners. It is in this scenario that scientists use GMO to move genes artificially between sexually incompatible partners.

Until humans can execute DNA, similar to a computer program, we will not be able to fully examine the effects of artificial DNA manipulation. The only way to find out is to grow the modified plant and then test it.

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