Detection of genetically modified soybeans by PCR method and immunoassay kits


The suitability of detecting genetically modified (GM) soybeans by polymerase chain reaction (PCR) and immunoassay kits is determined. Primers specific for inserted genes in the Roundup Ready™ soybean (RRS, Monsanto company) were applied. Four pairs of primers, namely, 35S (35S-promoter, originated from cauliflower mosaic virus), NOS (nopaline synthase-terminator, derived from Agrobacterium tumefaciens), EPSPS (5-enolpyruvylshikimate-3-phosphate synthase, obtained from A. tumefaciens strain CP4) and LE (endogenous gene lectin) were used to identify the GM soybeans. The detection limit of PCR was 0.1% (w/w) GM soybeans when primers 35S and EPSPS were used, and 1% when primers NOS were used. All soybean samples were evidenced by LE primer-PCR as soybean products. Results of Immunoassays by two kinds of kits, strip and ELISA were matched with PCR's, and feasibility of quantitation detecting GM soybeans is determined among 0∼2.5%. The data further revealed that the PCR method and immunoassay kits can sufficiently differentiate GM soybeans from non-GM products.

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