Abstract: 【Objective】 Rapeseed is one of the four major genetically modified (GM) crops, the production and application of GM rapeseed must be regulated in China. Performance of GMO detection is the prerequisite to implement GMO regulations, screening is the first step to determine the presence or absence of GMO ingredients in testing samples. Appropriate selection of screening targets can effectively reduce the chance of missed detection of some GM ingredients. A technical platform, involving establishment of screening strategy for GM rapeseed and development of a common reference plasmid that is compatible with the screening strategy, would provide technical support for regulating GM rapeseed.【Method】 Both regulatory elements and marker genes commonly used in GM rapeseed are obtained by collecting and analyzing the GM rapeseed varieties registered in database, then the screening strategy for GM rapeseed can be determined based on the principle of maximum coverage of GM rapeseed varieties. The whole nucleotide sequences of screening elements are collected by searching nucleotide database or retrieving patent. One screening target usually has multiple standard detection methods, both the primer pairs for conventional PCR and the primers/probe combinations for real-time PCR are aligned with the nucleotide sequence of each screening target to determine the target sequence that would be integrated into plasmid. The fusion sequence of all screening elements together with rapeseed reference genes was artificially synthesized, and cloned into the plasmid pUC18 to construct a positive plasmid molecule. Both conventional PCR and real-time PCR are utilized to evaluate the applicability of constructed plasmid as positive control.【Result】 The screening strategy for transgenic rapeseed was established by detecting nine elements, involving two promoters of CaMV 35S and FMV 35S, five genes of Bar, PAT, CP4-EPSPS, NPTII, and HPT, two terminators of NOS and PinII. This screening strategy achieved full coverage of transgenic rapeseed varieties with known information. The screening plasmid pYCSC-1905 was constructed for GM rapeseed, carrying nine screening elements and 2 rapeseed reference genes of HMG I/Y and CruA. The amplification efficiencies of nine screening elements and two rapeseed reference genes were in the range from 90% to 110%, demonstrating that the amplification efficiency of screening target is not influenced due to the mutual interference of integrated fragments. The plasmid pYCSC-1905 can be used as a common positive control for nine screening targets and two rapeseed reference genes, applicable to national standards (GB/T and Declaration of Ministry of Agriculture and Rural Affairs), Entry-exit inspection and quarantine industry standards (SN/T) and European Union standards.【Conclusion】 The screening strategy covering 9 elements for GM rapeseed screening , can achieve the screening of GM rapeseed in all stages from commercialization to safety assessment, and significantly reduce the missed detection of GM rapeseed. The developed plasmid pYCSC-1905 provides a general positive control for rapeseed screening and the standard methods, and ensures the accuracy and comparability of test results between laboratories.

Key words: genetically modified rapeseed, screening, screening strategy, positive plasmid molecule, application