Variations of tissue DNA density and nuclear DNA content in soybean lines and their impacts on the GMO quantification

The present study investigated the DNA density of the embryo, cotyledon, and seed coat of each soybean from 15 soybean cultivars, and evaluated the impacts of variations of tissue DNA density and nuclear DNA content in soybean lines on GMO quantification. The results have shown that DNA densities and DNA quantity ratios among the various tissues of soybean are significantly different from each other and have insignificant influence on the transgenic copy number and therefore on GMO quantification. The nature of the CRM and the transgenic material present in the analyzed sample has prominent impact on transgenic genome copies, thus on GMO quantification. The DNA densities of the various soybean-derived products are also distinctly different from that of the whole soybean, but which does not result in the similar differences on the GMO ratio among them. Nuclear DNA content of soybean is different from cultivar to cultivar. Results shows that variation of nuclear DNA content in soybean lines has a great impact on the accurate determination of GMO. In some extreme situations, the deviation amplitude can reach 26%, which is intolerable for accurate determination.