title: The combination of quantitative PCR and western blot detecting CP4-EPSPS component in Roundup Ready soy plant tissues and commercial soy-related foodstuffs.
abstract: With the widespread use of Roundup Ready soy (event 40-3-2) (RRS), the comprehensive detection of genetically modified component in foodstuffs is of significant interest, but few protein-based approaches have been found useful in processed foods. In this report, the combination of quantitative PCR (qPCR) and western blot was used to detect cp4-epsps gene and its protein product in different RRS plant tissues and commercial soy-containing foodstuffs. The foods included those of plant origin produced by different processing procedures and also some products containing both meat and plant protein concentrates. The validity of the 2 methods was confirmed first. We also showed that the CP4-EPSPS protein existed in different RRS plant tissues. In certain cases, the results from the western blot and the qPCR were not consistent. To be specific, at least 2 degraded fragments of CP4-EPSPS protein (35.5 and 24.6 kDa) were observed. For dried bean curd crust and deep-fried bean curd, a degraded protein fragment with the size of 24.6 kDa appeared, while cp4-epsps gene could not be traced by qPCR. In contrast, we found a signal of cp4-epsps DNA in 3 foodstuffs, including soy-containing ham cutlet product, meat ball, and sausage by qPCR, while CP4-EPSPS protein could not be detected by western blot in such samples. Our study therefore concluded that the combination of DNA- and protein-based methods would compensate each other, thus resulting in a more comprehensive detection from nucleic acid and protein levels.
  
  
  CONCLUSIONS
  The combination of quantitative PCR (qPCR) and western blot was used to detect cp4-epsps gene and its protein product in different Roundup Ready soy (event 40-3-2) plant tissues and commercial soy-containing foodstuffs. The foods included those of plant origin produced by different processing procedures and also some products containing a combination of both meat and plant protein concentrates. This study indicated that the combination of DNA- and protein-based methods would supplement each other for genetically modified detection from nucleic acid and protein levels. Accordingly, qPCR and western blot could be used in CP4-EPSPS detection in a wide variety of soy-related foodstuffs.
authors.affiliation: College of Life Sciences, Cooperative Demonstration Laboratory of Centrifuge Technique, Nanjing Agricultural Univ, Nanjing 210095, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Xiao
authors.forename: Honghong
authors.initials: H
authors.lastname: Wu
authors.forename: Xinghu
authors.initials: X
authors.lastname: Zhou
authors.forename: Sheng
authors.initials: S
authors.lastname: Xu
authors.forename: Jian
authors.initials: J
authors.lastname: He
authors.forename: Wenbiao
authors.initials: W
authors.lastname: Shen
authors.forename: Guanghong
authors.initials: G
authors.lastname: Zhou
authors.forename: Ming
authors.initials: M
authors.lastname: Huang
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D060054:Agrobacterium / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002681:China; D018744:DNA, Plant / Q000302:isolation & purification / Q000378:metabolism; D004351:Drug Resistance / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005513:Food Inspection / Q000379:methods*; D030841:Food, Genetically Modified; D005798:Genes, Bacterial; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology; D008461:Meat Products / Q000032:analysis; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D045730:Soy Foods / Q000032:analysis*; D030262:Soybean Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013025:Glycine max / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D018744:DNA, Plant; D004791:Enzyme Inhibitors; D005998:Glycine; D006540:Herbicides; D010446:Peptide Fragments; D011994:Recombinant Proteins; D030262:Soybean Proteins; D000097797:Glyphosate