Development and Interlaboratory Validation of a Novel Reproducible Qualitative Method for GM Soybeans Using...

Area of Science:

• Food Science
• Molecular Biology
• Genetics

Background:

• Genetically modified organism (GMO) labeling regulations are evolving globally.
• Japan's upcoming non-GMO labeling requires detecting GMOs at undetectable levels (limit of detection - LOD).
• Quantifying GMOs near the LOD is difficult as levels are often below the limit of quantification.

Purpose of the Study:

• To develop a qualitative method for detecting GMOs applicable to Japan's revised non-GMO labeling.
• To establish a reliable criterion for identifying samples exceeding the GMO threshold near the LOD.
• To enhance the reproducibility of GMO detection methods for regulatory purposes.

Main Methods:

• Developed a qualitative comparative Cq-based analysis targeting specific GMO sequences (cauliflower mosaic virus 35S promoter, GM soybean MON89788).
• Utilized ΔΔCq values derived from target and endogenous sequences as a criterion for exceeding the GMO threshold.
• Employed a standard plasmid to ensure stable and comparable ΔCq values, improving method reproducibility.
• Validated the method through an interlaboratory study.

Main Results:

• The developed qualitative method effectively determines if GMO content exceeds the regulatory threshold near the LOD.
• The use of a standard plasmid improved the stability and reproducibility of ΔCq values.
• Interlaboratory validation confirmed the method's robustness and applicability for detecting low-copy-number GMO DNA.

Conclusions:

• The novel qualitative detection concept provides a robust and reproducible approach for GMO analysis.
• This method is suitable for meeting the stringent requirements of revised non-GMO labeling regulations.
• The technique is particularly valuable for laboratories analyzing low-copy-number DNA samples.