The Basics of GMO Screening: Understanding Genetic Engineering in Crops
Genetically Modified Organisms (GMOs) have become a significant part of agricultural practices, especially in biotechnology-driven crops. These organisms have their genetic material altered through techniques that do not occur naturally, which can involve modifying plants, animals, or microbes. As biotechnology evolves, so too does the need for precise testing methods to detect GMOs, ensuring regulatory compliance, managing supply chains, and meeting international export requirements. This article explores the basics of GMOs, the importance of testing, and the various detection techniques used to maintain transparency and safety in food systems.
What Are GMOs?
GMOs, or genetically modified organisms, are organisms whose genetic material (DNA) has been altered in a way that doesn’t occur naturally. This modification can apply to various entities such as viruses, bacteria, fungi, plants, and animals. However, the focus in agriculture is primarily on biotech crops.
The World Health Organization (WHO) defines GMOs as organisms whose genetic material has been modified through unnatural processes. Similarly, the USDA’s National Bioengineered Food Disclosure Standard emphasizes the presence of detectable genetic material modified via laboratory techniques.
Traditional GMOs
Traditional genetic modification involves introducing a transgene, which combines genetic elements from different organisms. These include:
- Promoter: The "on switch" for gene expression (commonly derived from viruses).
- Gene of Interest: The primary trait (e.g., herbicide resistance).
- Terminator: The "off switch" (usually from bacteria).
Modern GMOs
Newer genome editing techniques, like CRISPR-Cas systems and TALENs, enable precise genetic modifications without introducing foreign DNA. These methods are cost-effective, highly specific, and faster to implement.
Why Test for GMOs?
- Regulatory Compliance
In the U.S., the USDA mandates bioengineered food labeling if detectable GM material is present. Testing helps manufacturers ensure compliance and avoid labeling risks.
- Supply Chain Management
Ingredient verification through GMO testing is crucial for risk management and meeting supplier requirements. Certifications or laboratory reports often accompany such tests.
- Export Requirements
Different countries have varying regulations for GMO labeling and approval, making testing vital for international trade.
GMO Testing: Methods and Applications
In North America, crops like corn and soybeans dominate GMO production. These genetically engineered varieties often exhibit traits like herbicide tolerance or pest resistance. Monitoring these crops involves detecting specific genetic sequences or traits through advanced testing methods.
Detection Techniques
Polymerase Chain Reaction (PCR)
- Ideal for detecting DNA in finished products, offering a broader array of GMO events.
- Offers both qualitative (presence/absence) and quantitative (amount) analysis.
- Is the standard method accepted by regulatory bodies for GMO detection.
- Has a higher degree of precision.
Enzyme-Linked Immunosorbent Assays (ELISA) and Lateral Flow Strip Tests (LFS)
- Used primarily for seeds and raw grains to identify proteins produced by GMOs.
- Provides a rapid (minutes) evaluation of the presence/absence of GMO proteins.
- Has challenges ln finished product matrices due to processing
Screening vs. Event-Specific Tests
Screening tests detect general GMO markers, such as the 35S promoter and Nos terminator, which are shared components across biotech products. Screening has its advantage in that it can detect multiple GMO events (but do not differentiate) in one broad stroke assay, however positive results may then require additional testing.
Event-specific tests identify individual GMO events that are unique to the biotech product, such as the integration site into the host genome.
Comprehensive GMO Screening Packages
Testing services, like those offered by Eurofins GeneScan, provide robust solutions for detecting GMOs in finished products. Comprehensive screening covers major GMO markers and a wide range of crop types, ensuring high accuracy and reliability.
Comprehensive screening can detect a wide range of GMO events across most GMO crop types, which is extremely useful in determining a finished product's GMO status when it has multiple ingredients that may be from different crop types that may be GMO.
A screening approach, utilizes:
- 35S promoter
- Nos terminator
- AgroBorder II element
Where, the CaMV 35S promoter and Nos terminator are the most prevalent promoter and terminator elements used and cover most GMO events, the AgroBorder II element is a common element of various GMO events that and extends that coverage by detecting events that may or may not be covered by the CaMV 35S promoter and Nos terminator.
The charts below highlight an example of some of the events covered by the Comprehensive GMO Screen in corn, soybean and canola. This list is not exhaustive, and newer events may not be reflected as they are developed.
Conclusion
As biotechnology advances, the importance of GMO testing grows. Whether for regulatory compliance, supply chain management, or market-specific requirements, thorough GMO screening ensures transparency and safety in our food systems.
For more information or specific testing needs,
