GM plants and their seeds may look no different from untransformed, parental material. Regulation of release consents, therefore, relies on test methods to detect the genes engineered into the crop, or the proteins produced in the plant by the introduced DNA. The SASA Diagnostic and Molecular Biology section conducts GM testing in support of the GM Inspectorate.

SASA uses DNA-and protein-based methods, which are highly sensitive and able to detect trace amounts of inserted DNA.

The DNA-based tests are based on conventional polymerase chain reaction (PCR) assays and are aimed at detecting genetic features that are unique to the inserted elements of a GMO.

The approach taken involves the correct sampling of the crop or crop product (i.e. seeds, grains and plants from a variety of crop plants including maize, oilseed rape, potato and soya), extracting the DNA and testing for the genetic modification. A wide variety of PCR primer sets are used in a step-by-step approach to identify unknown GM products.

Quantitative methods using real time PCR (TaqMan®) are also used. These methods offer the major advantage of being able to determine how much of a GMO is present in a sample.

In both cases, the assays are based on the detection of common gene promoters or terminators, or the traits themselves (Bt toxin gene, glufosinate tolerance gene, glyphosate, tolerance gene, etc.).

In association with this work, SASA belongs to a number of GM laboratory networks. These include

• The UK GMO Analytical Network organised by the Foods Standards Agency