Advance In Detection Methods Of Transgenic Soybean And Processed Products

Recently transgenic soybean and products have been increasing day by day and regarded as one of the main foods of human consumption directly or indirectly. People pay more and more attention to the effects of transgenic soybeans and the products on human's health and ecological environment. In order to meet consumer's right to choose and the right of being in know and to meet the needs of international business, the detection methods of the genetically modified food causes more and more attention of the food supervisory organization and the governments in all countries. With the labeling administration on genetically modified food in different countries and territories, the lowest limit of content in food have been already regulated, and threshold value becomes lower and lower. Quantitative detection is becoming more important. This requires all the countries not only to develope the qualitative methods with high facility and precision, but also to explore the quantitative way to meet the detection needs.However, the unified detection system has not been established internationally at present. For exploring the strategy for detection of introduced DNA, transgenic herbicide tolerance soybean (Roundup Ready, RR) and processed products have been used as materials to establishing the economic and reliable detection method in this study.The main results obtained are as follows: 1,To establish the DNA extracted methods from RR soybean and other processed products. Results indicate: DNAs in RR soybean have been extracted easily by CTAB methods and amplified clearly by conventional PCR. It's feasible for soy flour and defatted soy meal to extend the DNAs extracted time with 40min up to 60min. As for soybean oil, it's absolutely necessary to dissolve samples in TE liquid firstly. And as for soy sauce, wash samples at least twice or thrice with Tris-HCl (100mmoL/L) at first, it conduce to throw off lipochrome and amylose.2,The primers of the endogenous Lectin and introduced DNAs in RR soybean, i.e.CaMV35S promoter, NOS terminator and EPSPS have been designed and synthesized. Conventional polymerase chain reaction (PCR) were successfully used to amplify the endogenous Lectin and RR soybean specific genes in soybean, defatted soy meal, soy flour, oil and sauce. At last, Lectin gene was amplified and observed in all samples, other introduced genes were detected successfully in soybean, defatted soy meal and soy flour.3,CaMV35S promoter and NOS terminator were not detected in soy oil and sauce samples by conventional PCR method. Double pair of primers were designed and Nested-PCR was adoptted to amplify the CaMV35S promoter including 195bp and 117bp successfully. With the Conventional PCR, relative detection limits of transgenic content reached 0.1% and would be adequate for meeting needs of international detection.4,Amplifying Lectin gene as criterion to evaluate the sensitivity and accuracy of real-time fluorescence quantitative PCR.TaqMan^? probe was utilized in quantitative detecting of CaMV35S promoter and EPSPS in soybean and soy defatted meal. Results as follows: CaMV35S promoter and EPSPS standard curves were eatablished by standard transgenic RR soybean. On the basis of these two standard curves, the contents of trasgenetic factor in soybean samples were calculated with 3.02% and 3.00% expectively. In the same way, defatted soy meal were 3.48% and 3.49% expectively. Because of its good repeatability and reliability, TaqMan^? probe method is absolutely adequate for the quantitative detection of trasgenetic factor in RR soybean and defatted soy meal.