DETECTION OF GENETICALLY MODIFIED MAIZE FOOD PRODUCTS BY THE POLYMERASE CHAIN REACTION DETECCIÓN DE PRODUCTOS DE MAIZ GENETICAMENTE MODIFICADOS POR LA REACCIÓN EN CADENA DE LA POLIMERASA

• Published in: Ciencia y tecnología alimentaria 2006-12, Vol.5 (3), p.175-181
• Main Authors: Mendoza, A., Fernández, S., Cruz, M. A., Rodríguez-Perez, M. A., Resendez-Perez, D., Saldaña, H. A. Barrera
• Format: Article
• Language: English
• Subjects: genetically modified organisms; maize; p35S Palabras clave; PCR; soy
• ISSN: 1135-8122
• DOI: 10.1080/11358120609487689

A polymerase chain reaction (PCR) was applied to detect genetically modified (GM) maize and soybean food product, using specific 35S promoter primers for inserted chimerical genes in maize or soybean. The PCR detected food products that include ingredients obtained from GMOs in maize grains and flour, as well as processed in foods such as tortillas (Mexican crepe), corn chips, corn and soybean oils. Beside the promoter, the PCR also detected zeine and lectin genes for maize and soybean, respectively, which confirmed the identity of the analyzed samples. The presence of transgenic material was also confirmed by detecting the terminator Tnos region. High quality DNA from samples permitted an accurate detection of GM in food products while low quality DNA could lead to false negatives. The event Bt-176 and non-GM maize were used as positive and negative controls, respectively. Three types of GM food-products (grain, flour and soybean oil) resulted positive, while flour products (tortilla and corn chips) were negative and soy and corn oils also gave positive results. The amplified fragment corresponding to the 35S promoter was verified by sequencing that fragment. The PCR method detection limit was 0.1% (w/w) of GM content in the sample materials. In conclusion, PCR was effective in differentiating not only GM from non GM maize, but also such conditions in corn food products, revealed that marketed apparently non-GM maize products may have been elaborated with ingredients, and is sensitive enough to fulfill any possible requirements of the Mexican law (Biosafety Committee) in this matter. Resumen Para la detección de organismos genéticamente modificados (GM) provenientes de maíz, soya y sus derivados alimenticios se utilizó la reacción en cadena de la polimerasa (PCR) usando oligonucleótidos específicos del promotor 35S. La PCR detectó productos genéticamente modificados en granos y harinas así como también en productos procesados tales como tortillas, totopos y aceites comestibles de maíz y soya. Además del promotor, la PCR también detectó los genes de zeína y lectina para maíz y soja respectivamente, los cuales confirmaron la identidad de las muestras analizadas. La presencia de material transgénico fue también confirmada por la detección del terminador Tnos. La alta calidad de DNA de las muestras permitió una acertada detección de productos conteniendo GMs mientras que una baja calidad de podría dar falsos negativos. El evento Bt-176 y maíz no genéticamente