BACKGROUND: As labeling thresholds and low level presence thresholds of genetically modified (GM) components are implemented in more and more countries and regions, the demands for accurate quantification are increasing rapidly. At the same time, digital polymerase chain reaction (PCR) showed considerable benefits compared with former real-time fluorescence PCR in GM component quantification. RESULTS: A universal quantification method using duplex digital PCR was established for detection of transgenic soybean event DAS-68416-4. The absolute limits of quantification (LOQs) of DAS-68416-4 event-specific gene and lectin reference gene were 0.61 copies μL-1 and 4.6 copies μL-1 respectively in droplet digital PCR, while 0.522 copies μL-1 and 5.192 copies μL-1 in chip digital PCR. The relative LOQs of DAS-68416-4 percentage content was 0.1% in both two digital PCR systems. CONCLUSION: Gene copy ratio is the universal means of expression internationally used in transgenic component contents. Digital polymerase chain reaction (PCR) executes absolute quantification on specific genes, thus is considered to be suitable for detection of transgenic component contents. It was proved in this research on transgenic soybean event DAS-68416-4. Results indicated perfect satisfaction for transgenic component quantification needs in various technical performances of duplex digital PCR including repeatability, quantitative linear relationship and relative limits of quantification.
BACKGROUND: As labeling thresholds and low level presence thresholds of genetically modified (GM) components are implemented in more and more countries and regions, the demands for accurate quantification are increasing rapidly. At the same time, digital polymerase chain reaction (PCR) showed considerable benefits compared with former real-time fluorescence PCR in GM component quantification. RESULTS: A universal quantification method using duplex digital PCR was established for detection of transgenic soybean event DAS-68416-4. The absolute limits of quantification (LOQs) of DAS-68416-4 event-specific gene and lectin reference gene were 0.61 copies μL-1 and 4.6 copies μL-1 respectively in droplet digital PCR, while 0.522 copies μL-1 and 5.192 copies μL-1 in chip digital PCR. The relative LOQs of DAS-68416-4 percentage content was 0.1% in both two digital PCR systems. CONCLUSION: Gene copy ratio is the universal means of expression internationally used in transgenic component contents. Digital polymerase chain reaction (PCR) executes absolute quantification on specific genes, thus is considered to be suitable for detection of transgenic component contents. It was proved in this research on transgenic soybean event DAS-68416-4. Results indicated perfect satisfaction for transgenic component quantification needs in various technical performances of duplex digital PCR including repeatability, quantitative linear relationship and relative limits of quantification.