How are GMOS made

Expert response from Patrick Walker

Associate Scientist – Crop Pipelines, BASF Plant Science

Wednesday, 11/02/2015 14:52

I have been working in the plant biotechnology industry now for a little over three years and I find it fascinating that scientists are able to identify genes and genetically modify plants in order to meet global food, feed and energy demands. Corn, as many of you might know, is one of the most important cereal crops produced in the world. Corn is used as a main source of food for both humans and livestock and is also the leading crop used for bio-energy production.

Here at BASF Plant Science, we have many projects that aim to identify particular genes that may enhance a plant’s ability to survive under stressful conditions thus allowing a plant to produce the maximum amount of yield per acre of land. One of our projects is in collaboration with Monsanto that specifically focuses on developing corn that can grow under drought conditions. Some of you may remember hearing in the news in the last few years about the impact that drought can have on agriculture.  The U.S. was experiencing very dry conditions across the Midwest which was threatening to negatively impact corn yields.  If farmers cannot deliver good corn yields then it can impact food prices and thus consumers like us.  

Stress conditions like drought can be a very serious problem for farmers.  To help farmers reduce this risk, BASF and Monsanto  are using a number of platforms to discover genes that enhance the ability of a corn plant to more efficiently utilize the water that is available to it.

For many years, researchers have looked at ways to enhance the ability of plants to handle different types of stress, like drought in the laboratory, in greenhouses and in the fields where they are grown on a commercial level. In fact, if you have gone on vacation without watering your plants, you may have experienced the benefits of a plant that has genes that allow it to survive until you water it or other plants that don’t survive. Scientists and researchers take advantage of these types of experiments and observations in order to identify potential genes that may be suitable to transfer to plants such as corn.

This “transfer” of genes, or genetic material, can be done both traditionally, such as breeding one species of corn with another or through the use of technology that allows firms such as BASF to overcome some of the limitations of traditional breeding.

For thousands of years humans have cultivated and bred corn. With each passing year, we have selected the seeds from each harvest that contain the “genes” that provide us with a product that is tastier, that resists disease and drought conditions and ultimately yields the highest amount of corn per acre. Unfortunately, this type of genetic modification (traditional breeding) can take many years, sometimes decades, in order to produce a desirable end product.

Also, when traditional breeding techniques are employed, there is a transfer of a large amount of genetic material that, while allowing corn to grow under drought conditions, may also cause the corn to taste bitter or remain undesirable for consumption. Traditional breeding is also limited to the compatibility between species being crossed.

By utilizing biotechnology to genetically modify crops such as corn, scientists are able to only transfer the genes that confer drought resistance without transferring a bunch of other material that may affect other parts of the plant and cause them to be undesirable. This isn’t to say that we are abandoning traditional breeding; in fact, scientists use both approaches as complementary techniques in order to end up with the highest quality of genetically modified crops as possible.

The transfer of genes can be done in many ways. Today, the most common methodology for producing a genetically modified plant is to place plant cells in a container with a naturally occurring, soil-born bacterium known as Agrobacterium tumefaciens.

This species of bacteria is capable of taking up foreign genes, such as our drought-resistant genes by simply placing DNA that contains our desired gene(s) in the Agrobacterium. We then sterilize and isolate specific cells from our corn, and place the plant cells in a container with the Agrobacterium under sterile conditions.  The Agrobacterium then acts as it would in nature to transfer these “drought genes” into our corn cells. Once the drought genes enter the plant cells, they are incorporated into the genome just as the genes would if two corn plants were pollinated using traditional breeding techniques. Once the Agrobacterium has transferred the desirable genes into the corn cells, we then need to be able to grow those cells into a plant. We do this by practicing a technique called plant tissue culture.

Plant tissue culture is the practice of growing or maintaining plant cells that have been separated or isolated away from an intact plant. Maybe you have bought cut flowers before. When you buy the flowers you want your bouquet to contain some flowers that are open and some that are closed so your purchase lasts as long as possible. So, when you get them home you put them in a vase with some water and add a packet of “plant food”. Over time, the flowers that are open will stay beautiful and the buds that were originally closed will eventually open. Well, in its most basic form you have essentially practiced a form of tissue culture. You provide the plant cells (flowers connected to stems in this case) with light, water and some sort of nutrient in order to extend the beauty (the life) of the flowers in your home.

You also may have taken a cutting from a plant and placed it in water.  Soon the cutting will grow roots and you can then plant it in soil and you have successfully grown a new plant from cells, or a collection of cells (the cutting).

This concept is no different than what we do in the lab, although, instead of a flower or a house plant we are propagating plants that have been modified with genes that allow them to grow under drought conditions. Instead of using water alone we add the necessary nutrients and “solidify” the water (like Jello) using a naturally occurring substance called agar so that the plant cells don’t drown.

All of this work is conducted in special cabinets that purify the air so no ambient microorganisms are present. We also use bleach to sterilize the corn ears, just as you would at home to kill germs on your kitchen counter. We need to make certain that the only two organisms present are the Agrobacterium cells and our corn cells. Regardless of the types of materials we are working with, GMO or non-GMO, it is crucial for us to maintain a high standard of cleanliness and tidiness.

Also, see this infographic: The Lifecycle of a GMO.

Expert response from Bobby Williams

Senior Research Manager, DuPont Pioneer

Wednesday, 27/05/2015 12:42

This is a great question that really gets at the foundation of what I do in my job. When researchers make changes to the genetic make-up of a plant such as turning off an existing gene or adding a gene from another source to create a new, desirable characteristic (or trait), the resulting plants are considered GMOs. The process starts by defining the desired trait. For example, we might want to improve how a plant protects itself from insects, make a plant herbicide tolerant or increase the likelihood a plant will grow and yield in drought conditions. In order to find genes that have the desired function, nature is the first place we look.

Using insect control as an example, microbes that are toxic to the target pests were the starting point for many current GMOs. Molecular biologists studied those microbes and isolated the genes responsible for the insecticidal activity. These became candidate genes for testing in GMO plants. The bacterium Bacillus thuringiensis is the source of many insecticidal proteins used in current GMOs and the bacterium itself is used as a pesticide in many types of farming, including organic based farming.

The next step in GMO development is to transform a beneficial gene(s) into a crop plant. This is done by putting the gene into a molecular construct so that it can be inserted into a plant chromosome and effectively turned on. There are several other questions and answers on this site that describe the transformation process in detail, including this one.

Once the beneficial gene is inserted into the plant, making it a GMO, scientists will see if the gene is exhibiting the desired trait in crops. Getting back to the insect protection example, scientists then study whether the plants transformed with the bacterial insecticidal genes are more resistant to insects than the non-GMO controls. Extensive additional experiments are done to characterize the function of the insecticidal gene, optimize its ability to protect plants against infestation, test for any unintended effects to beneficial species as well as characterize performance in a field setting. (For more on the GMO approval process, see this response by my colleague).

A similar approach to that described above can be used to find genes from microbes or other plants that are naturally resistant to an herbicide or exhibit drought tolerance. So, the short answer is that nature is the first and best source for genes used in GMOs. Why invent something a new if nature has already evolved a good starting point?