Detection Methods Basics

Precise and accurate detection methods are developed, validated, and documented to
international standards during the development of each new genetically modified (GM) product.
These methods are integral to product development, quality control and regulatory data-
gathering, and are also essential to supporting efficient global trade and enforcing regional
regulatory frameworks.

Some regulatory bodies require provision of detection methods which detect the specific DNA or
proteins associated with the biotechnology-derived (biotech) trait unique to the GM product.
Thus, detection methods are used to ensure compliance with regulations. They are also used to
segregate and preserve the identity and purity of products. They are typically the intellectual
property of the trait developer(s). Detection methods are often made available to stakeholders
such as seed producers, grain handlers, food companies, and other stakeholders via licenses or
third-party testing laboratories.

The CropLife International Detection Methods website provides an avenue for stakeholders to
license these methods from the trait developer(s) to test for the presence of a GM product
(Principles for the Transfer and Use of Intellectual Property).

1 Types of Detection Methods

There are two primary types of detection methods in common use today for GM products. For a
more detailed discussion, refer to “Applications of Sampling and Detection Methods in
Agricultural Plant Biotechnology” (Shillito and Shan, 2022).

1.1 DNA-Based Methods

Polymerase chain reaction (PCR) is the analytical technique most preferred to detect and/or
quantify specific DNA sequence(s) present in GM product(s). PCR can be performed in a
qualitative manner to detect the presence or absence of a sequence or quantitatively to determine
the amount of target DNA present in a sample. “Event-specific PCR methods” are designed to
detect DNA sequences unique to a specific GM product. Alternatively, “genetic element-specific
methods” are designed to detect DNA sequences that may be common across several GM

PCR-based detection methods (PCR methods) are extremely sensitive, and thus able to detect
small amounts of a biotech product present in a sample, typically 1 seed in 1000 or better. The
PCR methods in the CropLife International Detection Methods Database are validated to meet
internationally accepted performance requirements. Performance and validation of PCR methods
is described in international standards (ISO 24276, Codex CXG74, ISO/DS 16393).  In addition,
there are a large number of publications available describing in detail the needs and requirements
for successful application of PCR methods.  Examples written by a group of authors from
CropLife International member companies, grain traders and private testing laboratories can be
found in Lipp et al. (2005) and Alarcon et al. (2019).

1.2 Protein-Based Methods

Protein-based detection methods (protein methods), such as immunoassays, determine the
presence or amount of a specific protein in plant tissues and derivative products (Lipton et al.
2000; Alarcon et al. 2019). Immunoassays require protein-specific antibodies and are often
employed in the form of an enzyme-linked immunosorbent assay (ELISA) or lateral flow strips,
also known as lateral flow devices (LFDs).

Protein detection methods are often easy to use. LFDs, for example, are well-adapted for field
use (Grothaus et al. 2006; Alarcon et al. 2019), are often commercially available in a kit format,
and are used extensively in the trading of commodities.

Protein detection methods are unable to distinguish between different biotech products that
express the same protein. Since proteins are often denatured by processing, protein methods are
most suitable for use on unprocessed or minimally processed materials (e.g., seed, plant tissues,
grain, flour). However, assays for use in specific processed materials have occasionally been
developed (Stave 2002).

2 Reference Materials

Reference Materials are used as standards in method calibration and if certified, must be
produced according to international standards (Trapmann et al. 2017) and guidelines. CropLife
International recognizes the need for reference materials for use in calibration and validation of
detection methods, as well as in proficiency testing of laboratories.

Certified Reference Materials (CRMs) are commercially available globally for all commercial
biotech crops developed by CropLife International members. These reference materials are
offered for single events by each company through designated ISO-accredited CRM providers.

3 References

Alarcon, C. M., Shan, G., Layton D.T, Bell, T.A., Whipkey, S., Shillito, R.D. (2019).
Application of DNA- and Protein-Based Detection Methods in Agricultural Biotechnology. J
Agric Food Chem 67(4): 1019-1028.

Grothaus, G. D., Bandla, M., Currier, T., Giroux, R., Jenkins, G. R., Lipp, M., Shan, G., Stave, J.
W., and Pantella, V. (2006). Immunoassay as an Analytical Tool in Agricultural Biotechnology.
J AOAC Int. 89 (4):913-928.

Lipp, M., Shillito, R., Giroux, R., Spiegelhalter, F., Charlton, S., Pinero, D., and Song, P. (2005).
Polymerase Chain Reaction Technology as Analytical Tool in Agricultural Biotechnology. J
AOAC Int. 88(1):136-155.

Lipton, C. R., Dautlick, J. X., Grothaus, G. D., Hunst, P. L., Magin, K. M., Mihaliak, C. A.,
Rubio, F. M., and Stave, J. W. (2000). Guidelines for the Validation and Use of Immunoassays for Determination of Introduced Proteins in Biotechnology Enhanced Crops and Derived Food
Ingredients. Food Agric Immunol. 12(2): 153-164.

Shillito R. and Shan G. (2022) Application of Sampling and Detection Methods in Agricultural
Plant Biotechnology. Woodhead Publ. & Cereals & Grains Assoc. Bookstore. ISBN:

Stave J.W. (2002). Protein Immunoassay Methods for Detection of Biotech Crops: Applications,
Limitations, and Practical Considerations, J AOAC Int. 85(3): 780–786.

Trapmann, S., Botha, A., Linsinger, T.P.J., Curtain, S.M., Emons, H. (2017) The new
International Standard ISO 17034: general requirements for the competence of reference material
producers. Accred Qual Assur 22: 381–387.

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