Development and application of a selective detection method for genetically modified soy and soy-derived products

Identification of an isogenic semidwarf rice cultivar carrying the Green Revolution sd1 gene by multiplex codominant ASP-PCR and SSR markers

The rice cultivar Hikarishinseiki, a semidwarf isogenotype of Koshihikari carrying the Green Revolution sd1 gene, is increasingly grown in both Japan and the United States. Here, we report DNA diagnosis for Hikarishinseiki targeting its Jukkoku-type sd1 locus, which codes for a defective gibberellin 20-oxidase, with a 1 bp substitution in exon 1 (Jukkoku-type GA20ox-2 mutant allele: Jukkoku_GA20ox-2). An allele-specific primer (ASP)-polymerase chain reaction (PCR) with primers SD1F3 and SD1JR gave a PCR product specific to Jukkoku_GA20ox-2. In addition, ASP-PCR with primers SD1F3 and SD1NRM (which contains a mismatch at the third nucleotide from the 3'-terminus of SD1NR) gave a PCR product specific to non-Jukkoku_GA20ox-2. Multiplex ASP-PCR using SD1F3, VIC dye-labeled SD1JR, and FAM dye-labeled SD1NRM enabled simultaneous codominant detection of Jukkoku_GA20ox-2 and non-Jukkoku_GA20ox-2 among 188 cultivars. Also, Hikarishinseiki is identifiable by RM253 polymorphism from 11 cultivars carrying Jukkoku_GA20ox-2. Taken together, our results establish a methodology for distinguishing Hikarishinseiki.

The impact of genetic modification of human foods in the 21st century: a review

Genetic engineering of food is the science which involves deliberate modification of the genetic material of plants or animals. It is an old agricultural practice carried on by farmers since early historical times, but recently it has been improved by technology. Many foods consumed today are either genetically modified (GM) whole foods, or contain ingredients derived from gene modification technology. Billions of dollars in U.S. food exports are realized from sales of GM seeds and crops. Despite the potential benefits of genetic engineering of foods, the technology is surrounded by controversy. Critics of GM technology include consumer and health groups, grain importers from European Union (EU) countries, organic farmers, environmentalists, concerned scientists, ethicists, religious rights groups, food advocacy groups, some politicians and trade protectionists. Some of the specific fears expressed by opponents of GM technology include alteration in nutritional quality of foods, potential toxicity, possible antibiotic resistance from GM crops, potential allergenicity and carcinogenicity from consuming GM foods. In addition, some more general concerns include environmental pollution, unintentional gene transfer to wild plants, possible creation of new viruses and toxins, limited access to seeds due to patenting of GM food plants, threat to crop genetic diversity, religious, cultural and ethical concerns, as well as fear of the unknown. Supporters of GM technology include private industries, research scientists, some consumers, U.S. farmers and regulatory agencies. Benefits presented by proponents of GM technology include improvement in fruit and vegetable shelf-life and organoleptic quality, improved nutritional quality and health benefits in foods, improved protein and carbohydrate content of foods, improved fat quality, improved quality and quantity of meat, milk and livestock. Other potential benefits are: the use of GM livestock to grow organs for transplant into humans, increased crop yield, improvement in agriculture through breeding insect, pest, disease, and weather resistant crops and herbicide tolerant crops, use of GM plants as bio-factories to yield raw materials for industrial uses, use of GM organisms in drug manufacture, in recycling and/or removal of toxic industrial wastes. The potential risks and benefits of the new technology to man and the environment are reviewed. Ways of minimizing potential risks and maximizing the benefits of GM foods are suggested. Because the benefits of GM foods apparently far outweigh the risks, regulatory agencies and industries involved in GM food business should increase public awareness in this technology to enhance worldwide acceptability of GM foods. This can be achieved through openness, education, and research.

Development of melting temperature-based SYBR Green I polymerase chain reaction methods for multiplex genetically modified organism detection

Commercialization of several genetically modified crops has been approved worldwide to date. Uniplex polymerase chain reaction (PCR)-based methods to identify these different insertion events have been developed, but their use in the analysis of all commercially available genetically modified organisms (GMOs) is becoming progressively insufficient. These methods require a large number of assays to detect all possible GMOs present in the sample and thereby the development of multiplex PCR systems using combined probes and primers targeted to sequences specific to various GMOs is needed for detection of this increasing number of GMOs. Here we report on the development of a multiplex real-time PCR suitable for multiple GMO identification, based on the intercalating dye SYBR Green I and the analysis of the melting curves of the amplified products. Using this method, different amplification products specific for Maximizer 176, Bt11, MON810, and GA21 maize and for GTS 40-3-2 soybean were obtained and identified by their specific Tm. We have combined amplification of these products in a number of multiplex reactions and show the suitability of the methods for identification of GMOs with a sensitivity of 0.1% in duplex reactions. The described methods offer an economic and simple alternative to real-time PCR systems based on sequence-specific probes (i.e., TaqMan chemistry). These methods can be used as selection tests and further optimized for uniplex GMO quantification.

Detection of genetically modified organisms in foods

Legislation enacted worldwide to regulate the presence of genetically modified organisms (GMOs) in crops, foods and ingredients, necessitated the development of reliable and sensitive methods for GMO detection. In this article, protein- and DNA-based methods employing western blots, enzyme-linked immunosorbant assay, lateral flow strips, Southern blots, qualitative-, quantitative-, real-time- and limiting dilution-PCR methods, are discussed. Where information on modified gene sequences is not available, new approaches, such as near-infrared spectrometry, might tackle the problem of detection of non-approved genetically modified (GM) foods. The efficiency of screening, identification and confirmation strategies should be examined with respect to false-positive rates, disappearance of marker genes, increased use of specific regulator sequences and the increasing number of GM foods.