Colorimetric vs. Real-Time LAMP for detection of genetic modifications in soybean (Glycine max)

Genetically modified food is becoming one of the greatest concerns in agriculture, especially owing to the continuously growing diversity of genetic modifications (GM), which is directly contributing to the difficulty of their monitoring and detection. Long-term impacts on human health and environment are yet to be revealed but recent research efforts indicate possible harmful effects. The aim of this study was to compare two approaches of GM detection: a naked eye detection via colorimetric LAMP method and a fluorescence-based Real-Time LAMP method. In order to imitate GMO samples, we prepared soybean leaf and seed gDNA spiked with gBlocks (P-35S and P-FMV elements which are most commonly included in transgenic constructs of GM plants). Additionally, we analyzed how different approaches for soybean gDNA isolation, i.e. robust Chelex-based method applicable in PON settings and a kit-based isolation suitable for laboratory conditions, influence LAMP amplification dynamics. There were no observable differences related to DNA isolation method in case of colorimetric LAMP, whereas Real-Time LAMP showed evidently faster amplification for DNA samples isolated with a commercial kit. Both LAMP approaches showed success in detection of GM for the threshold of 0.001 ng/μl of gBlocks in 1 ng/μl of total gDNA. We determined the same LOD for both Colorimetric and Real-Time LAMP methodologies, but this limit can be significantly enhanced in case of Real-Time LAMP, since this method has great potential for integration in biosensors with different signal readout systems (e.g. electrochemical or MXene-based). These results indicate the supremacy of Real-Time LAMP over colorimetric LAMP in terms of better insight into result accuracy and better reliability.