Purpose: To develop multiplex PCR assays that can specifically screen all currently approved GM crops from agricultural raw materials as well as processed food.
Methods: m-PCRs for screening 8 major GM crops including corn, soybean, cotton, potato, alfalfa, sugar beet, wheat, and rice were developed with primers targeting the most common genetic elements covering currently approved GM crops. Specificity and sensitivity of each assay were determined by testing against commercially available standard GM materials: - 12 GM corns, 8 GM soybeans, 9 GM cottons, 1 GM potato, 1 GM sugar beet, 1 alfalfa, 1 GM wheat and 1 GM rice - in different ratios of spiked GMO contamination. Also evaluated were differently processed foods ranging from bulk crops, cake mixes, and popcorns to highly processed foods such as cereal, nutrition bar, and canned vegetables.
Results: Eight different m-PCRs were developed for screening GM corn, GM soybean, GM cotton, GM sugar beets, GM alfalfa, GM potato, GM wheat, and GM rice. Each PCR assay specifically amplified GMO-specific elements from DNA purified from all 34 standard GM materials tested. All multiplex PCR assays detected 10-100 copies of target gene. The limit of detection was less than 0.01% (wt/wt) target DNA and less than 0.1% (wt/wt) target crop contaminations. These assays also detected GM crops from 55 distinctly processed food samples including powders and liquids as well as highly processed canned.
Significance: The m-PCRs approach developed in this study allows for simultaneous detection of GM crops in one reaction with adequate sensitivity. It is rapid and cost effective, and therefore, highly applicable to the screening of GMO.