5.3.3. Protein based methods

The basis of these methods is immunological and lays in the specific binding of the type “antigen – antibody” and classical ELISA assay. The antigen – antibody reaction recognizes the foreign molecule, binds to it and the bound complex thus obtained, is detected usually through a chromogenic reaction. Since the antibody, needed to detect the antigen, can not be developed without access to the purified antibody itself, the latter can be either artificially synthesized in the amino acid sequence is known, or purified from the GMO studied.

Generally the product of a transgene is a small polypeptide or a protein, which can be expressed under a strong constitutive promoter in any tissue and virtually during any time of the life cycle of the plant. In such a way the protein is in enough quantity to constitute an analytic target. However, in more recent GM plants the desired protein is only produced under the control of an inducible promoter (e.g. under stress conditions, during defined period of life-cycle, etc.). In these situation the detection and analysis of the presence of the recombinant protein is often not adequate.