The design of Plant Proteins screening methods for the detection of genetically modified organisms (GMOs) in food would improve the efficiency in their control.We report here a PCR amplification method combined with a sequence-specific electrochemical genosensor for the quantification of a DNA sequence characteristic of the 35S promoter derived from the cauliflower mosaic virus (CaMV).Specifically, we employ a genosensor constructed by chemisorption of a thiolated capture probe and p-aminothiophenol gold surfaces to entrap on the sensing layer the BALAY PADDLE unpurified PCR amplicons, together with a signaling probe labeled with fluorescein.The proposed test allows for the determination of a transgene copy number in both hemizygous (maize MON810 trait) and homozygous (soybean GTS40-3-2) transformed plants, and exhibits a limit of quantification of at least 0.25% for both kinds of GMO lines.