Testing for GMOs in Seed

“Dear Horticulture Talk,

How do you test seeds for GMOs?  I’m concerned because the companies I have been looking from keep saying that they don’t have GMOs in the seed to their knowledge.  Can’t they be sure?  I want them to be sure!




Hi Kyle,

Thanks for contacting Horticulture Talk through Facebook.

The procedures used to test seed to determine if the seed is genetically modified are ELISA (Enzyme-Linked Immunosorbent Assay) testing, protein strip analysis, or PCR (Polymerase Chain Reaction):

o   ELISA protein antibody tests are being used primarily to help farmers and elevators determine if a seed lot contains GMOs. Protein strip tests and ELISA tests are preferred for these types of applications because they allow relatively rapid turnaround times, and they require a relatively small investment in equipment and personnel. However, they do have some disadvantages that tend to limit their use. For example, ELISA or strip assays are limited to protein of specific events (e.g. Bt or RR) which often times are not readily available. Thus, strip tests and ELISA tests are not useful for detecting “any GMO” in a commodity or product.  Seed used for either testing method is destroyed because the test requires the seed to be crushed and dissolved in reagents needed to conduct the test.

o   DNA tests using PCR (Polymerase Chain Reaction) technology are also used to make decisions concerning the presence of GMOs, but more often are used for breeding, production and marketing decisions involving seed, grain, food ingredients, and finished food products. DNA/PCR methods are more sensitive, accurate, and robust and are generally considered to be the preferred method for detecting “any GMO.” As long as appropriate protocols, samples, and sample sizes are used, false positive or false negative results are extremely rare events.  PCR requires the seed to be crushed and heated.

By ‘to our knowledge’, it is the best that any seed company or seed producer can assure a customer.  No matter which test is used, all require that the seed used in the test be destroyed in order to produce results.  If one was basing their assumptions off of testing alone, there would be no seed to plant as each individual seed would have to be crushed for testing.

Instead, seed producers take a representative sample from each lot and it is tested for transgenes.  The plants used to produce seed are grown under laboratory or field conditions for seed breeding (i.e. Other pollens are not allowed, whether they are non-GMO pollen or GMO pollen, as the production of seed is regulated by law so that the same type of pollen is always used.  Contamination by non-GMO or GMO pollen would result in an ‘off-type’ plant that would not be true to type).  Once the seed has been harvested, it is given a lot identification to distiguish it from other lots of seed that may have been grown in a different area or harvested from the same place at a different time.  Each lot is then tested via PCR.  These tests are conducted by reputable, third-party testing facilities that can provide unbiased results.  If the lot contains even a trace of transgenes, it would be destroyed to prevent cross contamination.




© Mertie Mae Botanics LLC and Horticulture Talk!, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Mertie Mae Botanics LLC and Horticulture Talk! with appropriate and specific direction to the original content.

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