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The Scientific Scoop on GMO Testing

By Michelle Pelletier Marshall, Women in Ag Media (December 13, 2022)

(NOTE: This was first published in our sister publication, Unconventional Ag News)

There is much discussion in agriculture regarding GMOs, or genetically modified organisms. These organisms have been engineered to add specific traits, such as tolerance to herbicide application or production of an insecticidal protein. These traits increase the likelihood of a plant’s survival and thus increase crop yields. Modifications include the addition of various quality traits to the plant, such as drought tolerance, modified nutrient profiles, and others. As the industry evolves to incorporate these new technologies in the market, what is clear is the need for testing and how to measure for GMOs. Accurate testing allows for compliance with testing regulations so that foods can be accurately labeled for sale (65 countries currently require this), as well as facilitating trade and the accuracy of product labeling for seed sales.

One company that is at the forefront of this technology is Romer Labs, a leading global supplier of diagnostic solutions for food and feed safety with labs around the world, including Mexico, Germany, Canada, China, and Brazil. To understand this part of the equation better, Unconventional Ag News spoke to Donna Houchins, one of their scientists who is based in Union, Missouri.

Houchins is an analytical chemist by trade who has worked for more than two decades in R&D. She has extensive experience with the use and development of analytical methodology for food and commodity testing, including methods for detection of mycotoxins, food allergens, and GMOs. We asked her the following:

1). What are GMOs and why are they tested for?

GMO stands for “Genetically Modified Organism”. These are organisms (plants and animals) that have had novel traits added to them. These traits generally originate from a different organism. In commercially important plants, common modifications allow for herbicide tolerance or insect resistance. There also are traits such as drought tolerance and modified nutrient profiles. They are tested to satisfy buyer/seller contracts in grain, to comply with import/export requirements around the world, and also for quality control purposes.

2). Over 60 countries around the world, including Australia, Japan, and countries in the EU, require genetically modified foods to be labeled. How do your testing services come into play with helping with this food labeling/identification?

Buyers and sellers often have contracts in place based upon where they intend to sell their product. Various countries with labeling laws also require labeling at differing levels. Therefore, testing services are used by buyers and sellers to determine where they can sell which product, and with which label.

3). Please explain a bit about the different technologies available for detection of GMOs -- Qualitative LFD, Quantitative LFD, ELISA, and PCR.

Detection methods for GMOs generally fall into two categories: those that detect the novel protein produced by the modification, and those that detect the actual genetic change. Lateral Flow Devices (LFDs) and ELISAs test for the protein produced by the genetic modification. Most of these tests can only be used on raw materials, and not finished food or processed grain, as the processing steps often denature or destroy the protein. Lateral flow devices are extremely fast and simple to use, and for this reason, are typically the test of choice for field locations. They also are commonly used in grain elevators where speed is of the essence because the truck must be tested before it can be unloaded. They may be used for quality control purposes, or testing individual single seeds or leaf tissue in a field or greenhouse environment.

These tests may be quantitative or qualitative. Quantitative or qualitative use of these devices typically depends on what type of test is being done, and what buyer/seller contracts state. For example, single seed or leaf testing will only be qualitative, but a bulk grain buyer/seller contract may specify that only certain levels are allowed, so quantitative may be run. ELISAs require a laboratory environment to run, more highly trained staff, and take longer than LFDs to run, but many samples can be run at one time. They are sometimes more sensitive than LFDs as well. ELISAs are often utilized in laboratory environments where many samples must be run in batches. This may be for quality control (hundreds of single seeds or leaf samples run in a batch), or at food manufacturers where they are testing ingredients for their products.

PCR, in contrast to LFD, does not test for the modified protein. Instead, it tests for the actual genetic change that was made. Commonly in grain, promoters and terminators are tested for, which gives a broad-spectrum positive or negative result for many GMOs, without being specific for a particular one. Event-specific PCR may also be run if specific GMOs are of interest. PCR is a more expensive technology and takes longer to run than LFD or ELISA, so it is not suitable for rapid, single sample testing. It requires a laboratory environment and highly trained staff. However, it has the ability to detect lower levels of positives, and can also test some processed samples that most LFD or ELISA cannot. Therefore, it is often used for confirmation testing.

4). What information is important when deciding on a specific test method? And, is one detection technology better than another?

No one test method is “better” than another. Different tests are better suited to different tasks, and the needs of the user will determine which test is best for the task. In order to select a test method, the user will need to decide what information he or she needs. Items that should be considered include:

How quickly must the test be completed? Are single sample tests - run as quickly as possible - the priority, or can samples be saved and batched? Speed requirements favor lateral flow. The need to run many samples at once may favor ELISA.

What plant material do you need to run? Is it bulk grain, single seed, or leaf tissue?

What information is needed? Is there a contract with specifications that must be met? Do you need to know whether “any” GMO is present (test for as many as possible or broad-spectrum screening) or are you concerned about specific ones? Are qualitative results sufficient, or do you need quantitative? These items can help to choose a specific method within a technology (for example, lateral flow, ELISA, and PCR all have qualitative and quantitative methods).

If you need to test for specific GMOs, how specific do you need? Many events may produce the same protein, so protein testing will not tell you which event it is. However, event-specific PCR is available, if only one event is the target of testing.

Do you need quantitative results, or is qualitative sufficient?

5). Why is it important to test for GMOs? How is this information used by your clients?

Testing for GMOs is important for several reasons. First, testing is used for quality control by the trait providers to ensure that the seed that is being sold contains the traits that it is supposed to. Testing also is used by grain handlers and food manufacturers to facilitate the movement of grain around the world. These companies may have buyer/seller contracts that they are testing to fulfill, or they may be testing to comply with labeling requirements that exist in various countries.


Donna Houchins is a research and development specialist with Romer Labs. She has extensive experience with use and development of analytical methodology for food and commodity testing, including methods for detection of mycotoxins, food allergens, and GMOs using HPLC, LC-MS/MS, TLC, ELISA, lateral flow devices, and fluorometry.

She also has experience with development of reader systems for fluorometry and lateral flow devices. Houchins serves as co-chair on the AOAC Mycotoxin Community and is vice president of the Analytical Environmental Immunochemical Consortium (AEIC). She holds a bachelor’s degree in biology from Truman State University in Kirksville, Missouri, and an associate degree in biology and art from East Central College.


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