Detection and Quantification of Roundup Ready Soy in Foods by Conventional and Real-Time Polymerase Chain Reaction

Abstract

Transgenic soybean line GTS-40-3-2, marketed under the trade name Roundup Ready (RR) soy, was developed by Monsanto (USA) to allow for the use of glyphosate, the active ingredient of the herbicide Roundup, as a weed control agent. RR soy was first approved in Canada for environmental release and for feed products in 1995 and later for food products in 1996 and is widely grown in Canada. Consumer concern issues have resulted in proposed labeling regulations in Canada for foods derived from genetically engineered crops. One requirement for labeling is the ability to detect and accurately quantify the amount of transgenic material present in foods. Two assays were evaluated. A conventional qualitative Polymerase Chain Reaction (PCR) assay to detect the presence of soy and RR soy and a real-time PCR to quantify the amount of RR soy present in samples that tested positive in the first assay. PCR controls consisted of certified RR soy reference material, single transgenic soybeans, and a processed food sample containing a known amount of RR soy. To test real-world applicability, a number of common grocery store food items that contain soy-based products were tested. For some samples, significant differences in amplification efficiencies during the quantitative PCR assays were observed compared to the controls, resulting in potentially large errors in quantification. A correction factor was used to try to compensate for these differences.

Detection of genetically modified organisms in soy products sold in Turkish market

“…Soybean (Glycine max L.) comprises the major part of the GM crop species planted since the soybean-planted areas account for nearly 50% of the total world's GM planted areas (James, 2011). The first crop approved for food production was Roundup Ready (RR TM ) soybean in 1996, and it is now the most common transgenic Soybean line (Rott et al, 2004). It was developed by Monsanto and confers tolerance to Roundup herbicide.…”

Rapid Quantification Methods for Genetically Modified Maize Contents Using Genomic DNAs Pretreated by Sonication and Restriction Endonuclease Digestion for a Capillary-Type Real-Time PCR System with a Plasmid Reference Standard

“…PCR efficiency was calculated using the slope of the standard curve according to Formula 1, as follows. 31) Formula 1: PCR efficiency (E) ¼ 10 ðÀ1=slopeÞ…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Hence many real-time PCR systems based on fluorescent detection, such as TaqMan Ò chemistry, have been developed to identify and quantify GM maize, GM soybeans, and GM varieties of other agricultural commodities. [22][23][24][25][26][27][28][29][30][31][32][33] Real-time PCR systems using TaqMan Ò chemistry are based on the use of a fluorescent TaqMan Ò probe that monitors the formation of the PCR product during each cycle of the reaction. In addition, most commonly, GMO quantification by real-time PCR methods is calculated from the ratio of the target transgenic specific DNA sequence copy number vs. the DNA sequence copy number of the respective target plant species (taxon-specific sequence).…”

Transgenic Residues in Soybean-based Foods

“…The use of Dutp and UNG in the PCR reaction eliminates contamination, which is the major source of false positives. Rott et al (2004) evaluated two essays, one of conventional PCR to detect the presence of RR soybean. The second was realtime PCR to quantify the amount of RR soybean present in samples that were positive in the first essay.…”