Application of Digital PCR in Analyzing Monsanto Roundup Ready (RR) Soybeans

Detection and quantification of transgenes are important in analyzing genetically modified organisms (GMOs). Quantitative polymerase chain reaction (qPCR) is commonly utilized for such purposes. However, qPCR has certain limitations in detecting and quantifying transgenes in GMOs, such as the need of a reference standard and possible influence by inhibitors. Therefore, alternative and possibly better methods are needed. Recent advances in digital PCR technologies have promised to allow accurate quantification of nucleic acids and therefore provided another useful technique to analyze GMOs. Life Technologies (now part of ThermoFisher Scientific) has recently commercialized the QuantStudio 3D digital PCR system that can be used for a wide range of applications involving nucleic acids. It will be beneficial to the scientific community to show the applicability of this digital PCR system in detecting and quantifying transgenes in GMOs. In the present study, the transgenes present in the Roundup Ready Soybean (RR1, event 40-3-2) and Roundup Ready Soybean 2 (RR2, event  MON89788) developed by Monsanto Incorporation, were analyzed using this digital PCR system. qPCR analysis was also included as the comparison. Using specifically designed TaqMan assays, as low as 1% of the RR1 or RR2 soybean material was reliably detected and quantified on the dPCR platform. Therefore, digital PCR was a sensitive and reliable method to analyze the RR transgenic soybeans, and should be another useful tool for analyzing GMOs in general.