title: Relative quantification in seed GMO analysis: state of art and bottlenecks.
abstract: Reliable quantitative methods are needed to comply with current EU regulations on the mandatory labeling of genetically modified organisms (GMOs) and GMO-derived food and feed products with a minimum GMO content of 0.9 %. The implementation of EU Commission Recommendation 2004/787/EC on technical guidance for sampling and detection which meant as a helpful tool for the practical implementation of EC Regulation 1830/2003, which states that "the results of quantitative analysis should be expressed as the number of target DNA sequences per target taxon specific sequences calculated in terms of haploid genomes". This has led to an intense debate on the type of calibrator best suitable for GMO quantification. The main question addressed in this review is whether reference materials and calibrators should be matrix based or whether pure DNA analytes should be used for relative quantification in GMO analysis. The state of the art, including the advantages and drawbacks, of using DNA plasmid (compared to genomic DNA reference materials) as calibrators, is widely described. In addition, the influence of the genetic structure of seeds on real-time PCR quantitative results obtained for seed lots is discussed. The specific composition of a seed kernel, the mode of inheritance, and the ploidy level ensure that there is discordance between a GMO % expressed as a haploid genome equivalent and a GMO % based on numbers of seeds. This means that a threshold fixed as a percentage of seeds cannot be used as such for RT-PCR. All critical points that affect the expression of the GMO content in seeds are discussed in this paper.
authors: Laboratory of Genetics, Biodiversity and Bioresource Valorization, High Institute of Biotechnology of Monastir, University of Monastir, Avenue Tahar Haddad, BP74, 5000 Monastir, Tunisia. maher.chaouachi@gmail.com
authors: Maher
authors: M
authors: Chaouachi
authors: Aurélie
authors: A
authors: Bérard
authors: Khaled
authors: K
authors: Saïd
mesh_terms: D002138:Calibration; D005504:Food Analysis / Q000379:methods*; D030841:Food, Genetically Modified; D018628:Gene Dosage; D018745:Genome, Plant; D006238:Haploidy; D030821:Plants, Genetically Modified / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D012639:Seeds / Q000235:genetics*
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