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Development and Validation of a New Robust Detection Method for Low-Content DNA Using ΔΔCq-Based Real-Time PCR with
Keisuke Soga1, Kosuke Nakamura1, Tomohiro Egi2
1Division of Biochemistry, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki-ku, Kawasaki-shi210-9501, Kanagawa, Japan.
Analytical Chemistry
|October 7, 2022
Summary
A new real-time polymerase chain reaction (PCR) method enhances detection of low-content genetically modified (GM) maize DNA. This robust approach improves accuracy for food analysis and GM crop detection near the limit of detection.
Area of Science:
- Molecular biology
- Food science
- Biotechnology
Background:
- Real-time polymerase chain reaction (PCR) is crucial for DNA detection, but challenges persist in accurately quantifying low-content DNA samples.
- Existing methods for detecting genetically modified (GM) organisms, particularly in food, struggle with sensitivity and inter-laboratory variability, especially near the limit of detection (LOD).
Purpose of the Study:
- To develop and validate a robust real-time PCR method for the accurate detection of low-content genetically modified (GM) DNA.
- To address the variability in DNA quantification that affects the LOD in inter-laboratory studies.
- To establish a reliable method for GM food labeling verification.
Main Methods:
- Developed a ΔΔCq-based real-time PCR assay using specific primers for GM maize sequences (P35S, TNOS) and a maize endogenous gene (SSIIb).
- Utilized optimized standard plasmids with known concentrations as control samples to minimize variability in DNA input measurements.
- Evaluated the method's performance using GM maize event MON863 and certified reference materials.
Main Results:
- The ΔΔCq real-time PCR method demonstrated robust detection of GM maize DNA at concentrations as low as 0.2% MON863 genomic DNA.
- The use of optimized standards significantly reduced inter-laboratory variability in LOD determination.
- The method proved practical for detecting low-content GM crops in real-world samples.
Conclusions:
- The developed ΔΔCq real-time PCR method offers a reliable and accurate solution for detecting low-content GM DNA, overcoming limitations of traditional methods.
- This approach enhances the validation of GM food labeling and has broad applicability in various DNA detection fields.
- The method's robustness and improved accuracy make it a valuable tool for regulatory compliance and scientific research involving trace DNA analysis.
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