A team of researchers from the Government Chemist Programme, in LGC, have developed a new control material to help labs identify false positives when monitoring imports for genetically modified (GM) rice in food products originating from China.
The report on the control material has been published in a paper in the Journal of the Association of Public Analysts (JAPA).
For the study, the researchers synthesised a specific DNA sequence from Cauliflower Mosaic Virus (CaMV) and inserted it into a standard plasmid to provide a suitable control, and then tested using a validated and EU approved PCR assay.
The team was successful in amplifying the DNA target in the CaMV plasmid control while detecting approximately four copies of the plasmid target.
The P-35S promoter sequence, which is derived from CaMV, is one of the genetic elements screened in order to infer the presence of GM rice. It is also present in naturally occurring Cauliflower Mosaic Virus which can infect plants such as cauliflower and turnip and affect plant growth, while posing no risk to humans.
Therefore, the presence of the P-35S promoter sequence means that a consignment is contaminated with unauthorised GM rice, and laboratories must ensure that it is not a false positive from naturally occurring Cauliflower Mosaic Virus.
Malcolm Burns, one of the authors of the paper, said that testing for unauthorised GM rice is a complex task, where there is a need to provide assurance that the contamination is present beyond reasonable doubt.
"The control material we have developed means that for the first time labs can easily check that their work to avoid false positives is on a sound basis," Burns added.
The study, which is aimed at developing a suitable plasmid control DNA for CaMV, was carried out under the Government Chemist Programme in LGC and is funded by the National Measurement Office.
LGC, headquartered in Teddington, South West London, is a science-based company and is involved in the laboratory services, measurement standards, reference materials and proficiency testing marketplaces.
