One Novel Multiple-Target Plasmid Reference Molecule Targeting Eight Genetically Modified Canola Events for Genetically Modified Canola Detection

Development and verification of new reference plasmid (pUC_GM-SB) for the DNA-based detection of genetically modified sugar beet H7-1

The sugar beet is the second-largest sugar-producing crop. Genetically modified (GM) sugar beet, which have herbicide-resistant, have been developed to increase production and comprise over 90% of the market share. This study describes qualitative and quantitative PCR methods for the GM sugar beet H7-1 with reference plasmid (pUC_GM-SB) containing an endogenous gene (GS2) and an event-specific gene for H7-1 that served as a positive control for PCR. The detection limit of qualitative PCR was approximately 10 copies of the reference plasmid and 0.05% in spiked samples. In the case of quantitative PCR, the detection limit was five copies of the reference plasmid. Regarding repeatability, the standard deviation and relative standard deviation were found to range from 0.11 to 0.24 and from 0.23% to 0.99%, respectively. This study provides food safety assurance for imported GM sugar beet H7-1 using the reference plasmid and supports efficient detection methods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01572-6.

Development and collaborative validation of an event-specific quantitative real-time PCR method for detection of genetically modified CC-2 maize

As one of the developed genetically modified (GM) maize varieties in China, CC-2 has demonstrated promising commercial prospects during demonstration planting. The establishment of detection methods is a technical prerequisite for effective supervision and regulation of CC-2 maize. In this study, we have developed an event-specific quantification method that targets the junction region between the exogenous gene and the 5' flanking genomic DNA (gDNA) of CC-2. The accuracy and precision of this method were evaluated across high, medium, and low levels of CC-2 maize content, revealing biases within ±25% and satisfactory precision data. Additionally, we determined the limits of quantification of the method to be 0.05% (equivalent to 20 copies) of the CC-2 maize. A collaborative trial further confirmed that our event-specific method for detecting CC-2 produces reliable, comparable, and reproducible results when applied to five different samples provided by various sources. Furthermore, we calculated the expanded uncertainty associated with determining the content level of CC-2 in these samples.

Quantitative real-time PCR analysis of four genetically modified soybean events using plasmid and genomic DNA calibrators

A calibration curve is required for reliable and accurate quantitative real-time PCR analysis of genetically modified (GM) organisms, necessitating the use of reference materials as calibrators. In this study, two types of DNA calibrators-plasmid DNA (pDNA) and genomic DNA (gDNA)-were used to quantify four GM soybean events (SYHT0H2, MON87751, DAS-44406-6, and DAS-81419-2). The PCR efficiency and linearity for the calibrators adhered to the CODEX guidelines. The conversion factor (Cf) was calculated as the ratio of copies of GM events to those of endogenous genes using the pDNA calibration curve. To assess the accuracy and repeatability of these assays, quantification at GM levels of 3% and 1% was performed. Based on our results, we believe that the pDNA calibrator assessed in this study can be used as a reference material for GMO quantitative analysis and can replace gDNA, especially considering the ease of management and advantages of mass production.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01392-0.

Multiplex PCR detection method of genetically modified canola event (MON94100, LBFLFK, and NS-B50027-4) combined with capillary electrophoresis

Genetically modified organisms (GMOs) have been continuously developed for their convenience and productivity. In the past three years, three new GM canola events (MON94100, LBFLFK, and NS-B50027-4) have been developed. To efficiently control these GM canola events, the detection methods were needed. Therefore, the multiplex PCR method combined with capillary electrophoresis was developed for three GM canola events. Ten GM canola, eighteen GM soybean, thirty-two GM maize, and ten non-GM crops were used to evaluate the specificity of the method. The detection limit of the multiplex PCR assay was determined to be 0.005 ng in the DNA mixture and 0.1% in the spiked sample. The aim of this study was to establish multiplex PCR coupled with capillary electrophoresis for the newly produced three GM canola events. The developed method is expected to contribute to monitor the commercially available GM canola events.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01377-z.

A review on the identification of transgenic oilseeds and oils

Transgenic technology can increase the quantity and quality of vegetable oils worldwide. However, people are skeptical about the safety of transgenic oil-bearing crops and the oils they produce. In order to protect consumers' rights and avoid transgenic oils being adulterated or labeled as nontransgenic oils, the transgenic detection technology of oilseeds and oils needs careful consideration. This paper first summarized the current research status of transgenic technologies implemented at oil-bearing crops. Then, an inspection process was proposed to detect a large number of samples to be the subject rapidly, and various inspection strategies for transgenic oilseeds and oils were summarized according to the process sequence. The detection indicators included oil content, fatty acid, triglyceride, tocopherol, and nucleic acid. The detection technologies involved chromatography, spectroscopy, nuclear magnetic resonance, and polymerase chain reaction. It is hoped that this article can provide crucial technical reference and support for staff engaging in the supervision of transgenic food and for researchers developing fast and efficient monitoring methods in the future.

Establishment and Validation of Reference Genes of Brassica napus L. for Digital PCR Detection of Genetically Modified Canola

As an effective tool for genetically modified organism (GMO) quantification in complex matrices, digital PCR (dPCR) has been widely used for the quantification of genetically modified (GM) canola events; however, little is known about the quantification of GM canola events using endogenous reference gene (ERG) characteristics by dPCR. To calculate and quantify the content of GM canola using endogenous reference gene (ERG) characteristics, the suitability of several ERGs of canola, such as cruciferin A (CruA), acetyl-CoA carboxylase (BnAcc), phosphoenolpyruvate carboxylase (PEP), cruciferin storage (BnC1), oleoyl hydrolase (Fat(A)), and high-mobility-group protein I/Y (HMG-I/Y), was investigated by droplet dPCR. BnAcc and BnC1 were more specific and stable in copy number in the genome of Brassica napus L. than the other genes. By performing intra-laboratory validation of the suitability of ERG characteristics for the quantification of GM canola events, the ddPCR methods for BnAcc and BnC1 were comprehensively demonstrated in dPCR assays. The methods could provide technical support for GM labeling regulations.

Collaborative Ring Trial of the Applicability of a Reference Plasmid DNA Calibrant in the Quantitative Analysis of GM Maize Event MON810

Certified reference materials (CRMs) is one of the critical requirements in a quantitative analytical method, such as in the quantification of genetically modified (GM) contents in food/feed products. Plasmid-DNA-based CRMs are becoming essential in GM content quantification. Herein, we report the construction of one plasmid DNA calibrant, pMON810, for the quantification of the GM maize event MON810 which is commercially planted and used for food/feeds worldwide, and the collaborative ring trial was used to validate its applicability. pMON10 was proven to have high specificity for the MON810 event. The limit of detection (LOD) and limit of quantification (LOQ) of real-time PCR assays of MON810 event and maize endogenous gene using pMON810 as calibrant was 2 copies/μL and 5 copies/μL, respectively. A total of eight laboratories participated in the ring trial and returned valid test results. Each sample was performed with three repeats and three parallels in each repeat. Statistical analysis of the ring trial results showed that pMON810 as a calibrant had high PCR efficiency (ranging from 0.885 to 1.008) and good linearity (ranging from 0.9933 to 0.9997) in MON810 and endogenous gene real-time PCR assays. The bias between the test values and true values ranged from 4.60 to 20.00% in the quantification of five blind samples. These results indicate that pMON810 is suitable for use as a calibrant for the quantification of MON810 events in routine lab analysis or to evaluate detection methods for MON810, as well as being used as a substitute for the matrix-based CRM of MON810.

Applicability of plasmid calibrant pMON87712 for quantitative detection of the transgenic soybean MON87712

The transgenic glyphosate-tolerant soybean MON87712 event was developed by the agrochemical and agricultural biotechnology company Monsanto (USA) and commercialized in 2013. Due to the absence of matrix-based and genomic DNA-positive reference material for MON87712, it is very difficult to detect and monitor this event. In this study, we developed a recombinant 760-bp linearized plasmid, including 150 bp of the soybean endogenous lectin gene and 610 bp of the exogenous BBX32 gene plus its 3' flanking sequence of MON87712 by In-Fusion cloning technology. In addition, a duplex real-time polymerase chain reaction for the detection of MON87712 and the soybean endogenous lectin gene was established. By using this method, we achieved specific and quantitative detection of MON87712 in 45 other kinds of crops, with a detection limit of 10 copies/μl. This method provides a new technical means for the accurate detection of transgenic soybean MON87712, as well as technical support for the supervision of agricultural transgenic organisms.

Event-specific quantitative polymerase chain reaction methods for detection of double-herbicide-resistant genetically modified corn MON 87419 based on the 3'-junction of the insertion site

MON 87419 was one of the new transgenic corn events developed in US with the trait of herbicide resistance to both dicamba and glyphosate. To monitor unintended release of genetically modified organism in the future, as well as to meet GM-labeling requirements, it is requisite to develop a reliable method for the detection and quantification of MON 87419, an event-specific primer pair was designed to amplify the 3'-junction site between the endogenous genome sequence and the transferred DNA of GM event MON 87419, amplicons of desired size were produced by qualitative polymerase chain reaction (PCR) assay. For the validation of this quantitative method, the mixed samples containing 10%, 1%, and 0.1% MON 87419 ingredient were quantified. The precisions were expressed as relative standard deviations, deviated by 7.87%, 12.94%, and 19.98%, respectively. These results clearly demonstrate that the PCR methods we developed herein can be used for event-specific quantitative testing of the double-herbicide-resistant corn MON 87419.

Detection of GM Canola MS11, DP-073496-4, and MON88302 events using multiplex PCR coupled with capillary electrophoresis

As of 2020, 11 GM canola events have been authorized as food for humans in Korea. However, there are no simultaneous multiplex detection methods for 3 GM canola events (DP-073496-4, MON88302, and MS11). Thus, we established the multiplex polymerase chain reaction (PCR) method coupled with capillary electrophoresis to detect 3 GM canola events. To verify the specificity of event-specific primers, various GM crops of 3 GM soybean events, 6 GM maize events, 2 GM cotton events and 11 GM canola events were prepared. The limit of detection of the developed multiplex PCR was approximately 0.0125% for 3 GM canola events. Certified GM canola and stacked events were analyzed to validate the developed multiplex PCR. This study focuses on establishing multiplex PCR coupled with capillary electrophoresis for newly approved GM canola events and contributes to efficient monitoring GM canola samples in Korea.

Development and Interlaboratories Validation of Event-Specific Quantitative Real-Time PCR Method for Genetically Modified Rice G6H1 Event

The transgenic rice G6H1 was a new event with the traits of herbicide-tolerance and insect-resistant. Herein, we developed one event-specific real-time PCR method with high specificity and sensitivity for G6H1 event quantitative analysis, and validated its performance on practical samples quantification through a collaborative ring trial. A total of eight laboratories participated in this validation and quantified three blind G6H1 powder samples including DNA extraction and real-time PCR analysis. The statistically analyzed results from returned data confirmed its high PCR efficiency and good linearity, trueness, and precision, indicating that the developed G6H1 real-time PCR assay was accurate, reliable, and comparable for G6H1 identification and quantification.