Degradation Of Endogenous And Exogenous Genes Of Transgenetic Roundup Ready Soybean During Its Processing

In order to reveal the rule of the degradation of DNA, exogenous gene and non-target genes during different manufacturing processes from the soybean raw material to products, to provide the scientifically basement for the estimation of GMO food, to put the GMO food management in practice, the degradation of genome DNA, epsps gene, promoter CaMV35S and terminator nos genes in the steps such as milling, cooking, blending, homogenizing, sterilizing, spray drying, yeast-refining, and fermenting in the processes of Tofu, soymilk, soybean flour and sauce were investigated using GMO soybean and non-GMO soybean as the experimental materials by sensitive polymerase chain reaction system, multiplex polymerase chain reaction and real-time quantitative polymerase chain reaction detection method.The results were summarized as follows:1. Methods for qualitative and quantitative detection of transgenic component in genetically modified soybean products were established respectively, which provide sensitive, specific, simple and useful tools for soybean food products.2. The degradation of genome DNA, non-target genes and exogenous gene in various processing methods were studied according to the changes of the fragments' sizes of the three genes mentioned above.The lectin gene was affected during milling, sterilizing, spray drying, yeast-refining and fermenting manufacturing processes; the fragment of exogenous gene epsps had been degraded in milling, blending, homogenizing, spray drying, yeast-refining and fermenting manufacturing processes. Cooking had no effect on the DNA and epsps gene.CaMV35S promoter considered, the amplication fragment of primer 35S₁/35S₁, 35S₂/35S₂, and 35S₄/35S₄,had no change in the different manufacturing processes except primer 35S₃/35S₃'. The terminator nos gene was nearly not degraded in each step of manufacturing process of RR soybean products.3. The quantitative change of transgenic component of the four soybean products during different manufacturing process was investigated using real-time quantitative PCR detection method.The epsps gene degraded so that the content of GMO dropped to 0.435%; depositing is a biochemical reaction, this process degraded genome DNA and the content of GMO raised. The exogenous gene epsps was affected worse than genome DNA after shaping; the content of GMO in Tofu was 0.797%.The endogenous gene was seriously damaged during the process of the soybean flour by spray drying; therefore the content of transgenic component in the terminal product was higher than before. The content of transgenic component decreased because the exogenous gene was degraded when blending and homogenizing in the manufacturing of soymilk. However, sterilizing could aggravate the degree of the degradation of the lectin gene, so the component increased. The damage of epsps gene was more serious than that of lectin gene in all the steps of sauce process, meanwhile the content of GMO dropped continuously.