Multiplex Droplet Digital PCR Protocols for Quantification of GM Maize Events

Area of Science:

• Molecular Biology
• Biotechnology
• Food Science

Background:

• Quantitative polymerase chain reaction (qPCR) has been the standard for DNA quantification but is becoming less cost-effective for the increasing number of genetically modified organism (GMO) analyses.
• The need for high-throughput, cost-efficient, and accurate GMO detection methods is crucial for regulatory compliance and food safety.

Purpose of the Study:

• To develop and describe multiplex Droplet digital PCR (ddPCR) protocols for the accurate and cost-efficient quantification of genetically modified (GM) maize events.
• To compare the performance of multiplex ddPCR with traditional qPCR for GMO detection.

Main Methods:

• Development of two multiplex ddPCR protocols: a nondiscriminating assay for quantifying multiple GM maize events as a group and a discriminating assay for quantifying individual GM events.
• Utilized ddPCR technology for absolute quantification without standard curves, addressing amplification efficiency bias and improving accuracy at low target copy numbers.
• Designed assays for specific detection of European Union-authorized GM maize events and endogenous targets.

Main Results:

• The nondiscriminating protocol allows multiplex quantification of twelve EU-authorized GM maize events as a group using only two assays.
• The discriminating protocol enables simultaneous quantification of four individual targets (three GM events and one endogenous gene) in a single reaction.
• ddPCR demonstrated improved cost-efficiency and accuracy, particularly for low target copy number detection, compared to standard qPCR methods.

Conclusions:

• Multiplex ddPCR protocols provide a significant advancement in cost-efficiency and accuracy for GMO quantification, particularly for GM maize.
• These protocols are adaptable for the quantification of various DNA targets, offering a versatile tool for molecular analysis.
• ddPCR offers a superior alternative to qPCR for high-throughput GMO testing, enhancing regulatory monitoring and food traceability.