A sensitive detection method for genetically modified MaisGard (TM) corn using a nested PCR-system

The genetically modified corn 'MaisGard(TM)' (Monsanto, 'YieldGard(TM)' in the U.S.A.) is resistant to the European corn borer due to the insertion an d expression of the cryIA(b) gene from Bacillus thuringiensis ssp. kurstaki . This gene controlled by a 35S promoter from the cauliflower mosaic virus is flanked at its 5'-site by the corn-specific intron 1 of heat shock prote in 70 (hsp 70). MaisGard(TM) corn is already widely cultivated in the U.S.A . and may find its way to Europe as a component of a variety of food- and f eedstuffs. This work describes the development and evaluation of a sensitiv e and specific detection method for MaisGard(TM) corn using a nested polyme rase chain reaction (PCR) system. The system consists of an outer 401 bp fr agment spanning the region of the 35S-promoter to the hsp70 intron 1, and a n inner 149 bp fragment. The method was developed using a gradient cycler t o empirically determine the range and limits of annealing temperatures that can be used. The sensitivity of the method is 50 pg DNA when using pure tr ansgenic DNA, and 500 ng DNA when 0.01% of the analysed DNA is transgenic. No other tested transgenic corn, including Bt176 and Bt11 from Novartis and 'LibertyLink(TM)' (T25) from AgrEvo or conventional corn could be detected with the MaisGard(TM)-system, indicating the high specificity of the metho d for MaisGard(TM).